In an unusual admission, Group of Seven (G7) leaders have said in their final communique from a summit in Italy that they had failed to bridge differences over climate change with US President Donald Trump - and America was unable to join other countries in committing to the Paris Agreement.

“The United States of America is in the process of reviewing its policies on climate change and on the Paris Agreement and thus is not in a position to join the consensus on these topics,” the communique read.

“Understanding this process, the heads of state and of government of Canada, France, Germany, Italy, Japan and the United Kingdom and the presidents of the European Council and of the European Commission reaffirm their strong commitment to swiftly implement the Paris Agreement,” it added.

Donald Trump says Nato member states need to 'pay up'

Under pressure from allies, Mr Trump backed a pledge to fight protectionism, but refused to endorse the global Paris climate change accord, saying he needed more time to decide, with European diplomats frustrated at having to revisit questions they hoped were long settled.

Mr Trump, who has previously called global warming a hoax, tweeted that he would make a decision next week on whether to back the 2015 Paris Agreement on curbing carbon emissions following lengthy discussions with G7 partners.

“The entire discussion about climate was very difficult, if not to say very dissatisfying,” German Chancellor Angela Merkel said. “There are no indications whether the United States will stay in the Paris Agreement or not.”

Climate action groups were quick to condemn Mr Trump’s actions.

Roberto Barbieri, Executive Director of Oxfam Italy, said: “President Trump, more than anyone else, has assumed the role of spoiler-in-chief - blocking agreement on many of these key concerns that affect millions of the world’s poorest people.

“It is courageous that six of the G7 countries stood up to him and reaffirmed their commitment to deliver on the climate deal made in 2015,” he added.

Alden Meyer, director of strategy and policy at the Union of Concerned Scientists (UCS) said that Mr Trump “waffling” on the issue of whether to stay in or leave the accord was deeply damaging.

“President Trump’s ‘climate inaction plan’ is a threat to every American’s health and future prosperity,” he said.

In pictures: President Donald Trump on tour Show all 39 1 /39 In pictures: President Donald Trump on tour In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump and Saudi Arabia's King Salman bin Abdulaziz al-Saud arriving for a reception ahead of a banquet at Murabba Palace in Riyadh Getty Images In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump, accompanied by First Lady Melania Trump, and Saudi Arabia's King Salman bin Abdulaziz al-Saud being welcomed at Murabba Palace in Riyadh Getty Images In pictures: President Donald Trump on tour 20 May 2017 US President Donald J. Trump with King of Saudi Arabia Salman bin Abdulaziz Al Saud during a welcome ceremony with traditional sword dancers at Murabba Palace, in Riyadh, Saudi Arabia EPA In pictures: President Donald Trump on tour 20 May 2017 King of Saudi Arabia Salman bin Abdulaziz Al Saud with US President Donald J. Trump and wife Melania during a welcome ceremony at Murabba Palace, in Riyadh, Saudi Arabia EPA In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump adjusts the Collar of Abdulaziz Al Saud Medal, after it was bestowed upon him by Saudi Arabia's King Salman bin Abdulaziz Al Saud at the Royal Court in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 20 May 2017 Saudi Arabia's King Salman bin Abdulaziz Al Saud presents U.S. President Donald Trump with the Collar of Abdulaziz Al Saud Medal at the Royal Court in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 21 May 2017 Palestinians print posters depicting US President Donald Trump in preparations for his planned visit, in the West Bank town of Bethlehem Reuters In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump accompanied by first lady Melania Trump, his daughter Ivanka Trump and her husband White House senior advisor Jared Kushner, before delivering his remarks to the Arab Islamic American Summit in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump looks on as U.S. Secretary of State Rex Tillerson and Saudi Arabia's Crown Prince Muhammad bin Nayef exchange a memorandum of understanding Reuters In pictures: President Donald Trump on tour 21 May 2017 First Lady Melania Trump shares a laugh with a child during a visit to the American International School in the Saudi capital Riyadh Getty Images In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump holds a bilateral meeting with Bahrain's King Hamad bin Isa Al Khalifa AP In pictures: President Donald Trump on tour 22 May 2017 Israeli soldiers rest during preparations ahead of President Trump's landing in Tel Aviv, Israel Getty Images In pictures: President Donald Trump on tour 22 May 2017 First Lady Melania Trump makes her way to board Air Force One in Riyadh as she heads with her husband the US President to Israel Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump board Air Force One for Israel, the next stop in Trump's international tour, at King Khalid International Airport AP In pictures: President Donald Trump on tour 22 May 2017 Israeli soldiers wait for the arrival ceremony of US President Donald Trump at Ben Gurion airport near Tel Aviv, Israel AP In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump arrive aboard Air Force One at Ben Gurion International Airport in Lod near Tel Aviv, Israel Reuters In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump disembark Air Force One on arrival at Ben Gurion International Airport AP In pictures: President Donald Trump on tour 22 May 2017 US President Donald J. Trump and his wife, US First Lady Melania Trump are welcomed by Israeli Prime Minister Benjamin Netanyahu upon arrival at Ben Gurion Airport, in Lod outside Tel Aviv, Israel EPA In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and Israeli Prime Minister Benjamin Netanyahu sit during welcome ceremony in Tel Aviv AP In pictures: President Donald Trump on tour 22 May 2017 US First Lady Melania Trump chats wife Sara Netanyahu as US President Donald Trump chats to Israel's Prime Minister Benjamin Netanyahu during a welcoming ceremony to welcome Trump at Ben Gurion International Airport Reuters In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump delivers a speech upon his arrival at Ben Gurion International Airport in Tel Aviv Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump gestures during a press conference with Israel's President at the President's Residence in Jerusalem Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump watches as First Lady Melania Trump signs the guest book at the President's Residence in Jerusalem Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump walks with first lady Melania Trump in Jerusalem's Old City Reuters In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump visits the Western Wall, the holiest site where Jews can pray, in Jerusalems Old City Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump stands next to Rabbi Shmuel Rabinowitz at the plaza in front of the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City Reuters In pictures: President Donald Trump on tour 22 May 2017 US Secretary of State Rex Tillerson and White House senior advisor Jared Kushner leave notes at the Western Wall in Jerusalem Reuters In pictures: President Donald Trump on tour 22 May 2017 US First Lady Melania Trump touches the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City EPA In pictures: President Donald Trump on tour 22 May 2017 Ivanka Trump, assistant and daughter of US President Donald J. Trump, touches the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City EPA In pictures: President Donald Trump on tour 22 May 2017 President Donald Trump visits the Western Wall AP In pictures: President Donald Trump on tour 24 May 2017 US President Donald J. Trump arrives in a vehicle to Saint Damaso's Court for a private audience with Pope Francis in Vatican City EPA In pictures: President Donald Trump on tour 24 May 2017 Pope Francis walks past Ivanka Trump and First Lady Melania Trump on the occasion of the private audience with President Donald Trump, at the Vatican AP In pictures: President Donald Trump on tour 24 May 2017 Pope Francis exchanges gifts with US President Donald Trump during a private audience at the Vatican Getty Images In pictures: President Donald Trump on tour 24 May 2017 Pope Francis meets US President Donald Trump and his wife Melania during a private audience at the Vatican Reuters In pictures: President Donald Trump on tour 24 May 2017 Pope Francis with US President Donald J. Trump EPA In pictures: President Donald Trump on tour 24 May 2017 Pope Francis gets into is car after meeting with US President Donald Trump AP In pictures: President Donald Trump on tour 24 May 2017 President Donald Trump and his wife Melania look at the frescoed ceilings during their visit to the Sistine Chapel at the Vatican L'Osservatore Romano/Pool Photo via AP In pictures: President Donald Trump on tour 24 May 2017 US President Donald Trump security vehicles are seen in front of Air Force One before take off from Leonardo da Vinci-Fiumicino Airport in Rome, Italy Reuters In pictures: President Donald Trump on tour 24 May 2017 US President Donald Trump and First Lady Melania Trump wave to reporters before boarding the Air Force One to Brussels, at the end of a 2-day visit to Italy including a meeting with Pope Francis at the Vatican, at Rome's Fiumicino international airport AP

Some were more optimistic than Ms Merkel. French President Emmanuel Macron praised Mr Trump's “capacity to listen” and said “I found someone who is open and willing to deal well with us.”

The new French president, said that “I saw a leader with strong opinions on a number of subjects, which I share in part — the fight against terrorism, the willingness to keep our place in the family of nations — and with whom I have disagreements that we spoke about very calmly. I saw someone who listens and who is willing to work.”

Mr Macron said he told Trump that is “indispensable for the reputation of the United States and the interest of the Americans themselves that the United States remain committed” to the Paris agreement.

There was also relief that Mr Trump agreed to language in the final G7 communique that pledged to fight protectionism and commits to a rules-based international trade system.

During his election campaign last year, Mr Trump threatened unilateral tariffs on Mexican and Chinese goods and said he would quit the North American Free Trade agreement unless it is renegotiated to his liking. Earlier this week he called Germany “very bad” on trade because of its surplus with the United States.

“In the end we convinced them to include the fight against protectionism in the final communique, so that was a step forward,” said one European diplomat, who declined to be named.

Thousands march against Trump in Belgium

Meeting in a luxury hotel overlooking the Mediterranean sea, hosts Italy had hoped that the summit would focus on Europe's migration crisis and the problems of neighbouring Africa.

The internal G7 divisions and a suicide bombing in Manchester on Monday, that killed 22, overshadowed the Italian agenda, but on Saturday five African leaders joined the world power leaders to discuss their continent's potential.

Niger President Mahamadou Issoufou urged the G7 to take urgent measures to end the crisis in Libya — the point of departure for hundreds of thousands of refugees migrants looking for a better life in Europe. He also criticised them for not honouring aid promises to fight poverty in West Africa's poorest regions.

“Be it Niger, a transit nation, or the countries of origin, it is only through development that we will prevent illegal migration,” Mr Issoufou said.

Italy was disappointed not to receive more backing for its call to open up more legal channels for immigration to try to slow the flow of people risking their lives to reach Europe on flimsy boats from Libya.

“There was very strong opposition by the Americans and British who wanted to refocus on security and water down the expansive language on freedom of movement,” said a European diplomat, who declined to be named.

The final communique was just six pages long, against 32 pages last year, with diplomats saying the leaders wanted a simpler document to help them reach a wider audience.

After lengthy deliberation, the document included a separate threat, that was inserted into the 2016 G7 statement, to take additional action against Russia, if warranted, for its intervention in Ukraine.

The European Union and the United States imposed sanctions on Russia after Moscow annexed Crimea from Ukraine in 2014 and pledged to up the penalties if Russian interference in Ukraine intensified. Mr Trump's promise of warmer ties with Moscow had called into question the US commitment to sanctions.

Diplomats said that on other key international issues, such as Syria and North Korea, there was broad G7 agreement.

Security questions dominated initial G7 discussion on Friday and the leaders called on internet service providers and social media firms to “substantially increase” their efforts to rein in extremist content.

Mr Trump is due to return to Washington later on Saturday at the end of a nine-day tour of the Middle East and Europe — his first foreign trip since taking office. Unlike other G7 leaders, he is not due to give a press conference before flying out. US officials said he had enjoyed “robust” conversations with his allies in Sicily and had also learnt a lot — especially in the debate on climate change.