A strike would affect millions of commuters

An LU spokesman said there would be a meeting with the Rail, Maritime and Transport (RMT) union in an attempt to work out a deal on pay and conditions.

But RMT leader Bob Crow said that he had "no confidence whatsoever" in the LU managers involved in the talks.

The walkout is due to begin at 1830 BST on Tuesday 29 June and threatens to disrupt the network.

Mr Crow resigned from the board of Transport for London on Friday after a row with London mayor Ken Livingstone.

Dealing out misinformation will not settle this dispute, but serious negotiation can RMT leader Bob Crow Union boss quits transport board

He angered the union by saying that if he was an RMT member he would cross picket lines because the latest pay offer was "extremely generous."

Mr Crow accused LU of sending out a "scandalously misleading" bulletin to all employees on the latest offer aimed at resolving the pay row.

"Dealing out misinformation will not settle this dispute, but serious negotiation can," he said.

The union has rejected a 3% pay offer and is also calling for a shorter working week.

About 7,500 workers from London Underground and the Tube's private maintenance firm Metronet could take part in any possible industrial action.

This week the RMT called off a strike on Network Rail, scheduled to coincide with the Tube action, after the company table a better offer on pensions.