Most European Union citizens who are resident in Britain will not be able to vote in a referendum on its membership of the bloc, the government said on Monday.
Legislation for holding the referendum is to be introduced in parliament on Thursday, as Prime Minister David Cameron kicks off a diplomatic push for reforms in the 28-member bloc.
In a statement, his office said that the referendum would be "based on the general election franchise", meaning that citizens of most EU countries who are resident in Britain would not be able to vote.
As is normal in British general elections, British people aged over 18 and United Kingdom residents who are from Ireland or the Commonwealth -- the 53-member organisation mostly made up of countries formerly part of the British Empire -- will be able to vote.
This includes residents from the EU nations Malta and Cyprus.
"This is a big decision for our country, one that is about the future of the United Kingdom," a source in Cameron's office said.
"That's why we think it's important that it is British, Irish and Commonwealth citizens that are the ones who get to decide."
EU citizens living in Scotland were able to vote in its independence referendum in 2014, and can vote in British local government elections.
The decision was welcomed by Conservative parliamentarian Liam Fox, a prominent eurosceptic.
"This is a fitting response by the government," Fox said in a statement.
"Allowing EU citizens to vote in our referendum would have been an unacceptable dilution of the voice of the British people."
Commonwealth citizens in Gibraltar and British nationals who have lived abroad for fewer than 15 years would also be able to vote.
Cameron has vowed to secure reforms on issues like immigration, welfare eligibility and power to refuse further integration, before asking the electorate whether or not Britain should remain a member -- possibly as soon as 2016.
The Conservative leader has pushed ahead quickly to hold a referendum after winning a second term in office this month.
This week Cameron begins a flurry of diplomatic efforts, hosting European Commission president Jean-Claude Juncker for a "working dinner" at his country residence Chequers on Monday where they are expected to discuss the vote.
On Thursday and Friday Cameron will visit a series of European capitals, meeting the leaders of Denmark, the Netherlands, France, Poland and Germany to seek support for the EU reforms.
The prime minister aims to speak to all 27 other leaders of member states of the EU before a European Council summit at the end of next month.
On Sunday the centre-left Labour party said it would change its policy to support the holding of a referendum on EU membership, while continuing to campaign for Britain to remain in the bloc.
World media monitoring