The U.K. government said in a statement Monday that British, Irish and Commonwealth citizens over 18 who are U.K. residents will be eligible to vote in the referendum on Britain's membership in the European Union.

U.K. Prime Minister David Cameron has pledged to renegotiate Britain's ties with the EU and then hold an in-out referendum on membership in the bloc by the end of 2017, a move that could eventually result in the U.K. leaving the 28-member union.

The government will introduce a bill to Parliament outlining plans for an EU referendum on Thursday, the same day Mr. Cameron embarks on a tour of European capitals for a series of meetings with his counterparts to discuss reforms he is seeking from the EU.

The eligibility rules, based on rules for voting in the general election, mean that citizens of Commonwealth countries like Canada, South Africa and Cyprus who are U.K. residents will get a vote, but other EU citizens won't. U.K. nationals who have lived overseas for fewer than 15 years will be eligible. Members of Britain's upper house of Parliament, the House of Lords, will also be able to vote.

"It is time to put this right and to give people the choice—in or out," a government official said. "This is a big decision for our country, one that is about the future of the United Kingdom. That's why we think it's important that it is British, Irish and Commonwealth citizens that are the ones who get to decide."

Commonwealth citizens living in Gibraltar will be able to vote.

John Curtice, professor of politics at Strathclyde University, said the voting eligibility rules won't have a significant effect on the outcome of the referendum.

"You lose one pro-EU group but you gain another," he said, referring to the exclusion of EU citizens living in the U.K. and inclusion of U.K. citizens living abroad.

Mr. Cameron on Thursday will meet with Danish Prime Minister Helle Thorning-Schmidt over breakfast. He will then travel to the Netherlands for talks with Dutch Prime Minister Mark Rutte before ending the day with bilateral talks with President François Hollande over dinner. On Friday, Mr. Cameron will meet with Polish Prime Minister Eva Kopacz in Warsaw before ending the trip in Berlin where he will hold talks with German Chancellor Angela Merkel.

Since Mr. Cameron was re-elected earlier this month, he has met with leaders from Sweden, Poland and Hungary and the president of the European Council, Donald Tusk. On Sunday, he hosted Jean-Claude Juncker, the president of the European Commission, at his Chequers country residence to discuss EU reform.

A May 22 poll by YouGov PLC showed one in four people think Mr. Cameron will be able to negotiate a new relationship between Britain and the EU that is better for Britain. The same survey showed 44% of voters back staying in the EU, while 36% would vote to leave. The rest didn't know or wouldn't vote.

Write to Jenny Gross at jenny.gross@wsj.com

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