Boris Johnson will face a diplomatically testing tour of the Middle East after accusing British ally Saudi Arabia of being behind "proxy wars".

The senior Cabinet minister was slapped down by Downing Street over his comments, with Number 10 saying his views did not represent official Government policy.

Mr Johnson will deliver a keynote speech at a major regional conference in Bahrain today before heading to Saudi Arabia on Sunday.

Theresa May’s official spokesperson said the Foreign Secretary’s comments about the activities of the autocratic petro-state were his own view and did not reflect Government policy.

Ministers have previously officially refused to criticise Saudi Arabia despite widespread reports of it committing war crimes in its military campaign in Yemen and a dire human rights situation at home.

The Foreign Secretary himself has previously publicly defended the country from criticism, as well as defended the UK’s sale of billion of pounds of bombs to its armed forces.

Mr Johnson however told the Med2 conference in Rome last week: “There are politicians who are twisting and abusing religion and different strains of the same religion in order to further their own political objectives. That’s one of the biggest political problems in the whole region.

“And the tragedy for me – and that’s why you have these proxy wars being fought the whole time in that area – is that there is not strong enough leadership in the countries themselves."

He added: “That’s why you've got the Saudis, Iran, everybody, moving in and puppeteering and playing proxy wars.”

The footage of the conference, published in The Guardian newspaper, is embarrassing for Mr Johnson, who is due to visit the autocratic petro-state on Sunday.

A Saudi delegation was also present at the Gulf cooperation council in Bahrain this week, which Theresa May visited.

Questioned about the comments on Thursday, Downing Street said Saudi Arabia was “a vital partner for the UK, particularly on counter-terrorism, and when you look at what is happening in the region, we are supportive of the Saudi-led coalition, which is working in support of the legitimate government in Yemen against Houthi rebels”.

Asked again, the PM’s official spokesperson said: “I’ve set out what the PM’s views are, and those are the foreign secretary’s views, they are not the government’s views on Saudi and its role in the region.

“He will be in Saudi Arabia on Sunday and will have the opportunity to set out the way that the UK sees the relationship with Saudi Arabia, and the work we want to do with them and other partners in the region to bring an end to the appalling conflict in Yemen, in which only last night we saw the humanitarian suffering.”

Labour’s shadow foreign secretary Emily Thornberry said her party had been making the same argument as Mr Johnson “for months”, accusing the Government of hypocrisy.

“That argument has consistently been rejected by Boris Johnson in the House of Commons, but now these remarks in Italy have shown us what he really thinks,” she said.

Theresa May attended a plenary session on the second day of the Gulf Cooperation Council this week (Getty)

“If that is his genuine view, he needs to explain why he ordered his MPs to vote against Labour’s calls in October to suspend support for the Saudi-led coalition in Yemen, until a lasting ceasefire has been brokered and until alleged violations of international humanitarian law have been properly investigated.

“The Government cannot complain about Saudi Arabia's military actions one minute, then continue selling it the arms to prosecute those actions the next. We need to see some consistent principle in the UK’s foreign policy, not more shabby hypocrisy.”

The Liberal Democrats’ shadow foreign secretary Tom Brake said Mr Johnson was “for once” talking sense.

10 examples of Saudi Arabia's human rights abuses Show all 10 1 /10 10 examples of Saudi Arabia's human rights abuses 10 examples of Saudi Arabia's human rights abuses In October 2014, three lawyers, Dr Abdulrahman al-Subaihi, Bander al-Nogaithan and Abdulrahman al-Rumaih , were sentenced to up to eight years in prison for using Twitter to criticize the Ministry of Justice. AFP/Getty Images 10 examples of Saudi Arabia's human rights abuses In March 2015, Yemen’s Sunni President Abd-Rabbu Mansour Hadi was forced into exile after a Shia-led insurgency. A Saudi Arabia-led coalition has responded with air strikes in order to reinstate Mr Hadi. It has since been accused of committing war crimes in the country. Getty Images 10 examples of Saudi Arabia's human rights abuses Women who supported the Women2Drive campaign, launched in 2011 to challenge the ban on women driving vehicles, faced harassment and intimidation by the authorities. The government warned that women drivers would face arrest. Getty Images 10 examples of Saudi Arabia's human rights abuses Members of the Kingdom’s Shia minority, most of whom live in the oil-rich Eastern Province, continue to face discrimination that limits their access to government services and employment. Activists have received death sentences or long prison terms for their alleged participation in protests in 2011 and 2012. Getty Images 10 examples of Saudi Arabia's human rights abuses All public gatherings are prohibited under an order issued by the Interior Ministry in 2011. Those defy the ban face arrest, prosecution and imprisonment on charges such as “inciting people against the authorities”. Getty Images 10 examples of Saudi Arabia's human rights abuses In March 2014, the Interior Ministry stated that authorities had deported over 370,000 foreign migrants and that 18,000 others were in detention. Thousands of workers were returned to Somalia and other states where they were at risk of human rights abuses, with large numbers also returned to Yemen, in order to open more jobs to Saudi Arabians. Many migrants reported that prior to their deportation they had been packed into overcrowded makeshift detention facilities where they received little food and water and were abused by guards. Getty Images 10 examples of Saudi Arabia's human rights abuses The Saudi Arabian authorities continue to deny access to independent human rights organisations like Amnesty International, and they have been known to take punitive action, including through the courts, against activists and family members of victims who contact Amnesty. Getty Images 10 examples of Saudi Arabia's human rights abuses Raif Badawi was sentenced to 1000 lashes and 10 years in prison for using his liberal blog to criticise Saudi Arabia’s clerics. He has already received 50 lashes, which have reportedly left him in poor health. Carsten Koall/Getty Images 10 examples of Saudi Arabia's human rights abuses Dawood al-Marhoon was arrested aged 17 for participating in an anti-government protest. After refusing to spy on his fellow protestors, he was tortured and forced to sign a blank document that would later contain his ‘confession’. At Dawood’s trial, the prosecution requested death by crucifixion while refusing him a lawyer. Getty Images 10 examples of Saudi Arabia's human rights abuses Ali Mohammed al-Nimr was arrested in 2012 aged either 16 or 17 for participating in protests during the Arab spring. His sentence includes beheading and crucifixion. The international community has spoken out against the punishment and has called on Saudi Arabia to stop. He is the nephew of a prominent government dissident. Getty

He added: “This will be a huge embarrassment to May as she returns from her grubby tour of the Gulf, where she did her best to ignore human rights and desperately push trade at all costs.”

Andrew Smith of Campaign Against Arms Trade said: “Boris Johnson’s comments are a clear contrast from his public position, which has been to consistently praise the Saudi regime, despite it being one of the most abusive dictatorships in the world. If he believes them to be puppeteers for proxy wars, then why is he continuing to arm and support them?”