EU migrants and 16- and 17-year-olds will be denied a vote on Britain’s membership of the European Union, Downing Street will announce today, in a move that is likely to trigger the first big test of David Cameron’s authority in Parliament.

Under the proposals EU nationals living in Britain will be ineligible to vote, regardless of how long they have been in the UK, with the exception of Irish citizens.

The proposals will form part of the Government’s legislation for an EU referendum by 2017 and will be included in the Queen’s Speech on Wednesday.

Last night Labour said it would join forces with the Liberal Democrats and the SNP to table an amendment to the Bill that would extend the franchise to 16- and 17-year-olds. The Conservatives no longer have a majority in the House of Lords and could also face opposition in their own ranks in the House of Commons amongst some of their MPs who are now in favour of lowering the voting age.

“It would be fair to say that there is now a range of views in the party on this issue,” said one Conservative backbencher. “There are some MPs who are pro and some who are against.”

The case for reform has been strengthened following the Scottish referendum last year, which became the first plebiscite at which 16- and 17-year-olds had the vote.

“Best practice from the independence referendum must be followed – and that includes extending the vote in an EU referendum to 16- and 17-year-olds across the UK,” said Angus Robertson, leader of the SNP in Westminster.

“Scotland’s 56 SNP MPs will certainly seek to amend the legislation to ensure that young people are able to take part in the vote.”

A Labour spokesman added: “We will support 16- and 17-year-olds having a vote in the referendum, and we will take a position on any other amendments as they arise.”

Under the plans announced by Downing Street the electorate eligible to take part in the EU referendum will be based on the general election franchise rather than that used for local or European Parliament elections – where non-British EU citizens are allowed to vote.

However, unlike in normal general elections, members of the House of Lords as well as Commonwealth citizens in Gibraltar will be allowed to take part.

British, Irish and Commonwealth citizens over 18 who are resident in the UK will therefore be eligible to vote as well as UK nationals resident overseas for less than 15 years. The Conservatives had promised in their manifesto to scrap the time limit on UK nationals resident overseas voting, but a Downing Street source said it was too complicated to enact before the referendum.

Labour announced yesterday that it would no longer oppose the principle of a referendum but would seek to amend the legislation. With support from independent peers, this could lead to the Government’s first defeat in the House of Lords and potentially hold up the passage of the Bill.

“It is not inconsistent to say that our future is better in Europe than outside of Europe, but we want to see Europe change not only for this country. All around Europe they have got to address the question of people feeling that Europe is too centralised, insufficiently accountable and insufficiently in touch,” said Labour’s acting leader, Harriet Harman.

“So it’s perfectly possible to want to remain in a situation but to want it to change.”

Mr Cameron will meet the President of the European Commission, Jean-Claude Juncker, for a working dinner at Chequers tonight where he will outline British proposals for a reformed EU.

He will fly to Denmark on Wednesday evening after the Queen’s Speech for a working breakfast on Thursday morning with the Prime Minister, Helle Thorning-Schmidt.

He will then travel on to the Netherlands for discussions with the Prime Minister, Mark Rutte, before ending the day with bilateral talks with President François Hollande at the Elysée Palace.

On Friday, the Prime Minister will meet Poland’s Prime Minister Ewa Kopacz in Warsaw before concluding the trip in Berlin where he will hold talks with the German Chancellor, Angela Merkel.

Downing Street said the purpose of the talks would not be to outline a series of demands but to try to establish common ground among member states.

Denmark and the Netherlands in particular are seen as key UK allies on issues such as restricting benefit claims from other EU nationals and Mr Cameron will attempt to build common ground with them ahead of an EU summit next month where the British proposals will be discussed more formally.

“These visits are about the Prime Minister making the case that the British people have voted to renegotiate our relationship with Europe and pointing out that a party that wanted to withdraw altogether won more than 10 per cent of the vote.

“He will outline the areas where we have concerns and want reform but he will also be listening very carefully to what they have to say.”

Highlighting the Government’s new more positive European approach Lord Hill, the Conservative European Commissioner appointed last year by Mr Cameron, said yesterday that there was an “extraordinarily strong case” for Britain to remain in the EU and warned that leaving would damage business and international relations.

“I think people will be making the case in the UK and EU of business benefits to our membership, the benefits to Britain for geopolitics and our diplomacy, the benefits to be able to try to deliver trade agreements. Those to me all seem like an extraordinarily strong case to stay in.

“If you look at the alternative they quickly seem to be less attractive than some people are suggesting.”

But highlighting the deep Conservative divisions on the issue, the former Environment Secretary Owen Paterson accused Lord Hill of propagating “scare stories”.

“They think they’re ahead in the polls, that they have us on the run,” he said.