The government and the Conservatives have condemned RMT plans to hold simultaneous strikes next week on the trains and tube.

Union chief Bob Crow announced on Monday that industrial action arising from two separate disputes would be held on the same day.

The strikes will begin at 6.30pm on June 29 and will continue for 24 hours.

The RMT said Network Rail had "effectively reiterated its refusal to negotiate on pensions".

And it also attacked London Underground and its contractors Metronet BCV and Metronet SSL for failing to reach agreement on pay and conditions.

"Our ballot for industrial action may have brought Network Rail to the negotiating table, but on pensions they have simply sat there with their arms folded," said Crow.

And he told tube managers: "We want a date for the implementation of a 35 hour week and a date for the start of a four day week, and we want serious progress on pay.

"We will not accept the destruction of hard-won working conditions, and we will not accept the creation of a two-tier workforce."

Responding to the announcement, transport secretary Alistair Darling said the strike was "totally unnecessary".

And shadow transport secretary Tim Yeo said the move would "cause inconvenience and suffering for passengers".

"The railways don't need any more disruption.  They need stability to get on with the job," he said.

"This is not the way to solve a dispute.

"Those who will be affected most by strike action are the long suffering passengers who have to endure one in five trains arriving late and cutbacks in services in some areas."