Between 20 to 30 Labour peers did not vote for the party in the recent European elections, ITV News understands.
Sources in the House of Lords told ITV News that "a large number" of Labour peers had opted to vote for different parties because of Labour’s Brexit policy.
At least 20 and as many as 30 Labour peers apparently raised concerns that their party’s position was too ambiguous and ultimately voted for others.
The Labour Party fell to third place in the European elections, falling behind the Brexit Party and the Liberal Democrats.
One former Labour minister confirmed they did not vote for the party last week but fell short of confirming which party they supported.
“Labour lost votes to the Lib Dems and to the Brexit Party. It is a major problem and I am not sure how it can be resolved,” the minister said.
Another said there that many Labour parliamentarians were "unhappy" with what they had seen during the election campaign from the leadership.
Earlier today ITV News learned that Cherie Blair, the wife of former Labour prime minister Tony Blair, had voted for the Liberal Democrats, while Mr Blair’s former director of communications Alastair Campbell was expelled from the party after he admitted to doing the same.
Reacting to the news about Mrs Blair and Mr Campbell Labour leader Jeremy Corbyn said: "I’m not in favour of getting people out of the party, I’m in favour of everyone in the party campaigning for the Labour Party."