London Mayor Boris Johnson branded the Tube union action over pay and jobs - due to start at 7pm (1800 GMT, 2pm Singapore time) unless a last-ditch agreement was reached - as 'ludicrous and unnecessary disruption'.

'Londoners and commuters trying to do their level best to cope with the most challenging economic climate for a long time will be furious at this decision,' Mr Johnson said.

'I urge (unions) to stop disrupting the lives of millions of people, put the needs of their members and of Londoners first, get back to the table and reach an agreement.'

Extra buses were set to be deployed and Tube tickets would be valid for overground trains to try to alleviate the impact of closing down a system used by millions of Londoners every day.

Mr Bob Crow, head of the Rail Maritime and Transport Workers' union (RMT), defended the strike threat after talks with management broke down on Monday.

'Not only could the management side not reach an agreement on the kind of deal needed to end this dispute, they also found it difficult to stick to existing agreements on redundancies,' he said.

'The strike will now go ahead and we expect it to be solidly supported.' Hours before the threatened strike, reports suggested that last-ditch talks were due to be held aimed at resolving the dispute, but it was unclear if they could break the deadlock.

The Football Association (FA) is considering playing a planned World Cup qualifier between England and Andorra at Wembley Stadium on Wednesday evening without allowing fans in if the Tube strike goes ahead.

'The FA and Wembley are closely monitoring the situation and will convey any subsequent implications for England's World Cup qualifier against Andorra as soon as anything is confirmed by the authorities,' said an FA statement. -- AFP