LONDON (AFP) - Prime Minister David Cameron will start face-to-face discussions at a summit Friday with European partners on renegotiating Britain's position in the European Union ahead of an in-out referendum by 2017.
On his first foreign trip since winning a general election earlier this month, Cameron is set to meet some of Europe's leading figures as he seeks to secure reforms over issues including immigration.
The Eastern Partnership summit in the Latvian capital Riga from Thursday focuses on how the 28-member bloc should reconcile its commitment to six former Soviet states with its relationship with Russia.
But it will also signal the start of Cameron's renegotiation push, a painstaking process likely to last for months which the British leader says will require EU treaty change.
"It's the first overseas visit for the prime minister since the election and it's his first opportunity to have some discussions with partners about the way he wants to reform the European Union, renegotiate the UK's relationship with it and the referendum," Cameron's spokesman told reporters.
"The package of measures outlined will need treaty change," he said.
Under pressure from eurosceptics, the British prime minister promised in 2013 to hold a referendum on whether Britain should leave Europe by 2017 if he won the general election.
Having secured victory on May 7 with a surprise though slender majority, he is now under pressure to hold the vote sooner rather than later.
Some senior members of his centre-right Conservative party have called for it to take place in 2016, along with Andy Burnham, a prominent contender to be next leader of the main opposition Labour party.
Nigel Farage, leader of the anti-EU UK Independence Party which has been riven with splits since winning only one seat at the election, believes the referendum will be held in May next year.
Farage warned in comments on BBC Radio 4's Today programme of "a great stitch-up where the European Commission and the European Council are seen to give some cosmetic concessions to Britain.
"Mr Cameron cries victory, on the basis of that we're supposed to support him in the referendum," he said.
Cameron's spokesman said that the plan was to hold it "by the end of '17 - if we can do it earlier then we would look at that".
A pledge to make the referendum happen is expected to be tabled in the Queen's Speech, which outlines the government's legislative programme, on Wednesday next week. The bill itself is expected to be tabled the day after.
Election win 'could strengthen hand'
Cameron says he will campaign to stay in Europe in the referendum as long as he can secure the reforms he says are necessary.
Opinion polls currently indicate that Britain would vote to stay in the EU.
Some of Cameron's main goals include controlling migration by making it harder for EU migrants to claim state benefits in Britain, opting out of the EU's commitment to "ever closer union" and handing powers back to national parliaments.
The Conservatives also want to compel any jobseeker from an EU country to leave if they have not found work within six months.
European Commission chief Jean-Claude Juncker says he is ready to work with Cameron for "a fair deal", opening the door to minor EU treaty change but insists key EU principles such as freedom of movement are non-negotiable.
Britain is a member of the EU but has kept its own currency rather than adopting the euro and is not part of the Schengen Area, the group of 26 European countries which have abolished passport and border controls at common borders.
A string of business leaders in Britain have spoken out against the possibility of a "Brexit".
The president of employers' group the Confederation of British Industry, Mike Rake, will urge businesses Wednesday to "speak out early" in favour of remaining part of a reformed EU.
European affairs think-tank Open Europe on Tuesday released an optimistic assessment of Cameron's chances of securing reform on issues such as EU migrants' access to welfare payments.
Its head of economic research Raoul Ruparel said Cameron's election win could help "dramatically" by boosting his authority with other EU leaders.