London Underground staff have started a 48-hour strike in a row over ticket office closures, after Prime Minister David Cameron said the action would “inflict misery” on Londoners.
He urged union leaders on Tuesday to call off the strike, which is now likely to cause travel chaos in the capital over the next few days.
The spokesman said Mr Cameron "thinks that Bob Crow's strike is plain wrong and Bob Crow should call it off rather than inflict misery on hard-working families in London".
The comments followed a confrontation between London mayor Boris Johnson and Mr Crow, the Rail Maritime and Transport union (RMT) general secretary on an LBC radio show.
The row broke out after the general secretaries of the RMT and the Transport Salaried Staffs Association (TSSA), Bob Crow and Manuel Cortes, today went to City Hall in an attempt to confront Boris Johnson.
They have accused Mr Johnson of failing to meet them to discuss the closure of ticket offices.
The mayor was at the central London studios of LBC radio for his weekly phone-in, when Mr Crow spoke to him on his mobile from outside City Hall.
"We are not here to score points - all we want is an opportunity to negotiate about the Tube.
"We are asking you to listen to our point of view. We would love to call the strike off."
Mr Crow accused the mayor of refusing to suspend the ticket office closures.
Mr Johnson replied: "That is complete nonsense. We are more than happy to engage on these issues.
"Of course there are job losses involved but there are no compulsory redundancies.
"We have already had more than 1,000 people showing an interest in voluntary redundancy.
"Call off this pointless strike which will do nothing other than cost your members their wages."
Mr Crow said later it was clear the mayor was still refusing to meet unions.
The ongoing tube strike is expected to services for 48-hours, and at the same time next week.
Transport for London warned that services will be hit on Tuesday until Friday morning, causing travel chaos for passengers.
Ahead of the radio show this morning Mr Crow said: "We have exchanged letters with Boris Johnson and it's now time to meet face to face - if he won't come to us then we are showing our willingness to engage by travelling to him. This dispute is too important for London for anyone to retreat into their bunker.
"We are making it clear again today that if Boris Johnson lifts the threat to jobs we will suspend the action to allow for fresh talks from a clean slate. It is not too late for Boris to take up that fair and reasonable offer and we are at City Hall to make it happen."
Mr Cortes of the TSSA added: "It is time for Boris to stop playing politics with the Tube. He may impress the right wing of the Tory Party by picking a fight with us but he is doing no favours to the travelling public.
"They want what we want. A properly staffed, safe and secure tube network."
On Monday, the London Mayor Boris Johnson accused rail union boss Bob Crow of holding London to ransom ahead of the two strikes. His comments came after photographs appeared in the press showing Mr Crow sunbathing on a beach in South America.
In his weekly column for the Daily Telegraph, the mayor said that while he did not begrudge Mr Crow his holiday, he was not entitled to "disrupt the lives of millions of people who are not on holiday but who want to work".
Mr Crow hit back, however, and stressed that his holiday was "booked up well before" the strike action. Mr Crow was also questioned about whether his high-profile was a distraction and how much the holiday cost, with some claiming it was £10,000.
"If I'm going to spend £10,000 on a car, or if I'm going to spend £10,000 on a holiday, or £10,000 on cigarettes, that's up to me," said Crow.
"I'm not being a distraction at all. What do you want me to do? Sit under a tree and read books of Karl Marx every day?" he added.