Bulgaria and Romania should “immediately” join the EU’s borderless Schengen area, the president of the European Commission has said.

Jean-Claude Juncker used his annual state of the union address to propose a series of reforms to the EU – mostly concerned with tighter integration and averting a so-called two-speed Europe.

As well as the expansion of the borderless area, the president proposed action to encourage all applicable EU members to adopt the euro as their currency. Mr Juncker proposed the creation of a new programme to provide technical and financial assistance to would be adopters.

The European Parliament and European presidencies also needed reform, Mr Juncker said – laying out proposals for trans-national lists and a single unified EU presidency..

Addressing the expansion of Schengen, Mr Juncker argued: “A more united Union also needs to become more inclusive. If we want to strengthen the protection of our external borders, then we need to open the Schengen area of free movement to Bulgaria and Romania immediately.

“We should also allow Croatia to become a full Schengen member once it meets all the criteria.

“If we want the euro to unite rather than divide our continent, then it should be more than the currency of a select group of countries. The euro is meant to be the single currency of the European Union as a whole.

“All but two of our Member States are required and entitled to join the euro once they fulfil all conditions.

“Member States that want to join the euro must be able to do so. This is why I am proposing to create a Euro-accession Instrument, offering technical and even financial assistance.”

Donald Tusk's role of European Council president would be rolled into that of Mr Juncker under plans unveiled by Mr Juncker (AP)

Some parts of the Schengen agreement have been temporarily suspended in recent years to deal with Europe’s migration crisis – with some countries re-introducing temporary border controls.

The area includes 26 European states – 22 of the 28 EU states, plus Iceland, Liechtenstein, Norway, and Switzerland. Ireland and the UK have opted out. There are no passport checks for any travel between countries within the area.

Other structural reforms to the EU proposed in the speech include plans for some members of the European Parliament to be elected by trans-European lists – a move which would see all 500 million EU citizens vote for the same sets of candidates in popular elections for the first time ever. Mr Juncker admitted the idea would face opposition from some existing MEPs, but argued that "such lists would help make European Parliament elections more European and more democratic".

Refugee crisis - in pictures Show all 27 1 /27 Refugee crisis - in pictures Refugee crisis - in pictures A child looks through the fence at the Moria detention camp for migrants and refugees at the island of Lesbos on May 24, 2016. AFP/Getty Images Refugee crisis - in pictures Ahmad Zarour, 32, from Syria, reacts after his rescue by MOAS (Migrant Offshore Aid Station) while attempting to reach the Greek island of Agathonisi, Dodecanese, southeastern Agean Sea Refugee crisis - in pictures Syrian migrants holding life vests gather onto a pebble beach in the Yesil liman district of Canakkale, northwestern Turkey, after being stopped by Turkish police in their attempt to reach the Greek island of Lesbos on 29 January 2016. Getty Images Refugee crisis - in pictures Refugees flash the 'V for victory' sign during a demonstration as they block the Greek-Macedonian border Refugee crisis - in pictures Migrants have been braving sub zero temperatures as they cross the border from Macedonia into Serbia. Refugee crisis - in pictures A sinking boat is seen behind a Turkish gendarme off the coast of Canakkale's Bademli district on January 30, 2016. At least 33 migrants drowned on January 30 when their boat sank in the Aegean Sea while trying to cross from Turkey to Greece. Getty Images Refugee crisis - in pictures A general view of a shelter for migrants inside a hangar of the former Tempelhof airport in Berlin, Germany Refugee crisis - in pictures Refugees protest behind a fence against restrictions limiting passage at the Greek-Macedonian border, near Gevgelija. Since last week, Macedonia has restricted passage to northern Europe to only Syrians, Iraqis and Afghans who are considered war refugees. All other nationalities are deemed economic migrants and told to turn back. Macedonia has finished building a fence on its frontier with Greece becoming the latest country in Europe to build a border barrier aimed at checking the flow of refugees Refugee crisis - in pictures A father and his child wait after being caught by Turkish gendarme on 27 January 2016 at Canakkale's Kucukkuyu district Refugee crisis - in pictures Migrants make hand signals as they arrive into the southern Spanish port of Malaga on 27 January, 2016 after an inflatable boat carrying 55 Africans, seven of them women and six chidren, was rescued by the Spanish coast guard off the Spanish coast. Refugee crisis - in pictures A refugee holds two children as dozens arrive on an overcrowded boat on the Greek island of Lesbos Refugee crisis - in pictures A child, covered by emergency blankets, reacts as she arrives, with other refugees and migrants, on the Greek island of Lesbos, At least five migrants including three children, died after four boats sank between Turkey and Greece, as rescue workers searched the sea for dozens more, the Greek coastguard said Refugee crisis - in pictures Migrants wait under outside the Moria registration camp on the Lesbos. Over 400,000 people have landed on Greek islands from neighbouring Turkey since the beginning of the year Refugee crisis - in pictures The bodies of Christian refugees are buried separately from Muslim refugees at the Agios Panteleimonas cemetery in Mytilene, Lesbos Refugee crisis - in pictures Macedonian police officers control a crowd of refugees as they prepare to enter a camp after crossing the Greek border into Macedonia near Gevgelija Getty Images Refugee crisis - in pictures A refugee tries to force the entry to a camp as Macedonian police officers control a crowd after crossing the Greek border into Macedonia near Gevgelija Getty Images Refugee crisis - in pictures Refugees are seen aboard a Turkish fishing boat as they arrive on the Greek island of Lesbos after crossing a part of the Aegean Sea from the Turkish coast to Lesbos Reuters Refugee crisis - in pictures An elderly woman sings a lullaby to baby on a beach after arriving with other refugees on the Greek island of Lesbos after crossing the Aegean sea from Turkey Getty Images Refugee crisis - in pictures A man collapses as refugees make land from an overloaded rubber dinghy after crossing the Aegean see from Turkey, at the island of Lesbos EPA Refugee crisis - in pictures A girl reacts as refugees arrive by boat on the Greek island of Lesbos after crossing the Aegean sea from Turkey Getty Images Refugee crisis - in pictures Refugees make a show of hands as they queue after crossing the Greek border into Macedonia near Gevgelija Getty Images Refugee crisis - in pictures People help a wheelchair user board a train with others, heading towards Serbia, at the transit camp for refugees near the southern Macedonian town of Gevgelija AP Refugee crisis - in pictures Refugees board a train, after crossing the Greek-Macedonian border, near Gevgelija. Macedonia is a key transit country in the Balkans migration route into the EU, with thousands of asylum seekers - many of them from Syria, Afghanistan, Iraq and Somalia - entering the country every day Getty Images Refugee crisis - in pictures An aerial picture shows the "New Jungle" refugee camp where some 3,500 people live while they attempt to enter Britain, near the port of Calais, northern France Getty Images Refugee crisis - in pictures A Syrian girl reacts as she helped by a volunteer upon her arrival from Turkey on the Greek island of Lesbos, after having crossed the Aegean Sea EPA Refugee crisis - in pictures Refugees arrive by boat on the Greek island of Lesbos after crossing the Aegean sea from Turkey Getty Images Refugee crisis - in pictures Beds ready for use for migrants and refugees are prepared at a processing center on January 27, 2016 in Passau, Germany. The flow of migrants arriving in Passau has dropped to between 500 and 1,000 per day, down significantly from last November, when in the same region up to 6,000 migrants were arriving daily.

Another significant reform proposed in the speech was the idea of merging the posts of European Commission president and European Council president. The President argued that “Europe would be easier to understand if one captain was steering the ship".

"Having a single President would better reflect the true nature of our European Union as both a Union of States and a Union of citizens," he said.

Such a proposal will face push-back from some member states, however – who see the Council president as representing their interests against those of the Commission.