Former London Mayor Ken Livingstone has dismissed the criticism of Unite's actions in the Falkirk Constituency Labour Party, saying he is delighted the trade union has recruited more members.

A day after Kim Howells, the former Labour Foreign Office Minister, warned Ed Miliband that he had to take action to tackle the trade union movement's hold over the party, Mr Livingstone, an ex-Labour MP, came to Unite's defence.

The selection in the seat, he insisted, "can't be fixed because everybody in that constituency will have the same vote.

"The Labour Party membership has halved since 20 years ago and in many areas we struggle to have anything like a functioning party. Now it's started to turn round for Ed Miliband and I'm delighted trade unions are encouraging their members to join in and get involved".

Mr Livingstone said union members would get a ballot and "if they don't like the Unite candidate, they don't have to vote for them".

He said: "It's a secret ballot and all that you will have in Falkirk is more members with the right to vote than there were a year ago."

Last month, an internal report considered by Labour's ruling National Executive Committee found "sufficient evidence for concern" about the legitimacy of some new recruits to the Falkirk party following claims Unite had stuffed it with its members.

Len McCluskey, the Unite leader, insists his union has done nothing wrong and has threatened legal action against the party.