Leader of RMT transport union accuses Ed Miliband of dancing to the tune of Tony Blair over automatic union affiliation to Labour

The leader of the RMT, Bob Crow, is to call on trade unions to break ties with Labour and create a new party that "speaks for working people".

Crow accused Ed Miliband of showing unions contempt and "dancing to the tune of Tony Blair" following the Labour leader's plans to end the automatic affiliation of union members to the party.

Although the transport union was expelled from the party in 2004 for allowing Scottish branches to affiliate to other political parties, Crow claimed Miliband's reforms were an attempt to "hack away at the last remaining shreds of influence held by those who created the party".

At Saturday's Durham miners' gala, one of the country's most traditional trade union events, the RMT general secretary will attempt to rally support for a "new party of labour" to take on the "anti-worker" agenda of the three main political parties.

Last year Miliband became the first Labour leader in more than two decades to address the gala, but he will not attend on Saturday.

Speaking ahead of the event, Crow said: "Over the past week we have seen Ed Miliband dancing to the tune of Tony Blair and the rest of the New Labour conspirators as he seeks to hack away at the last remaining shreds of influence held by those who created the party that he leads, the trade unions.

"If others want to stick around and be insulted by those whose only interest is our money and not our ideas then that's a matter for them, for the rest, there is a whole world of opportunity outside the constraints of the Labour party and RMT would urge them to embrace it and join us in this new political project.

"This is a moment of huge opportunity for all those sick and tired of Labour's embrace of pro-business, pro-EU, neo-liberal policies and we should seize it with both hands.

"With the latest assault by Labour on the unions the time is right to start building an alternative political party that speaks for the working people and the working class communities that find themselves under the most brutal attack from cuts and austerity in a generation. The time for the alternative party of labour is now."

Miliband launched plans for significant reform of the Labour party's relations with the trade unions earlier this week - a move Tony Blair hailed as "a real act of leadership".

The measures were designed to draw a line under the biggest crisis of Miliband's leadership, sparked by claims that Unite tried to fix the selection of Labour's general election candidate in Falkirk by packing the constituency with 100 or more of its own members, some of them without their knowledge. An internal party report on the allegations has been handed to police.

Miliband said events in Falkirk represented "part of the death throes of the old politics", and he hoped to usher in an "open, transparent and trusted" system which would engage more union members directly in the party.

Rather than being automatically affiliated to Labour unless they opt out of their union's political levy, union members should be asked to make an active decision to join the party by opting in.

The explosive reaction expected from the unions did not materialise, however, as Unite general secretary Len McCluskey told how he was "very comfortable" with the proposals.