KEN Livingstone has revealed his stop-over in Cuba and aborted trip to Venezuela cost Londoners a "modest" £29,637.

The mayor was left stranded in Cuba last week after Venezuelan president Hugo Chavez said he was "too busy" electioneering to sign an oil deal with Mr Livingstone.

The London Assembly demanded the mayor reveal the full cost of the trip - which included eight officials from his office.

Mr Livingstone and his four officials stayed in Havana for six days at a cost of more than £13,146, including £11,086 on flights, £1,530 on accommodation, £132 on meals, £195 on transport and £202 on phone and internet lines.

Another four officials flew directly to Venezuela at an estimated cost of £16,491, including £12,948 on flights.

The costs of unused tickets and other facilities have yet to be calculated by the mayor's office.

The entourage returned to London on Wednesday, with the cheap oil deal in doubt and political opponents calling the trip a "disgraceful waste of public money" and a "screw-up of colossal proportions".

The mayor was invited to Cuba by British Olympic Association chair Lord Colin Moynihan to attend the World Sport for All Congress.

His office said that as the host of the 2012 Games, "London has to develop close relations with other key Olympic players". Mr Livingstone, who is not a sports enthusiast, attended the last three hours of the week-long meeting.

The main purpose of the trip was to sign a deal which would have seen cheap Venezuelan oil for London's buses exchanged for advice on policing, tourism, transport and waste disposal.

"Given that Cuba plays a central role in the international Olympic and sporting movement, particularly in fields like boxing, I would have undertaken the trip to Cuba even without going on to Venezuela," Mr Livingstone said.

"If we can secure an agreement with Venezuela tens of thousands of the poorest Londoners will benefit from cheap travel.

"In light of the benefits these costs of the international promotion of London are extremely modest and those on my visit to Cuba in line with the costs incurred on other Mayoral trips. Similarly, the costs of the advance trip by key staff to Venezuela to prepare for a visit to attempt to secure an agreement benefiting the worst off Londoners were also modest compared to the potential benefits."

Liberal Democrat leader Mike Tuffrey said the mayor's explanation for his trip to Cuba "did not wash".

"He can protest as much as he likes but this trip has cost London tax payers at least £35,000 - all so he could attend, for less than 20 minutes, a minor meeting at an IOC conference," Mr Tuffrey said.

"And what is so far uncosted in this whole exercise is the amount of staff time involved in arranging his useless trip to South America."

Mr Livingstone said that since he was elected in 2000 he had spent an average of 10 days a year - less than three per cent of the time - on mayoral trips abroad.

To give a scale of the importance of London's international connections 516,000 Londoners, one in seven, are employed by foreign firms and 280,000 Londoners are employed in the tourist industry," the mayor said.

"The promotion of London abroad is therefore one of the most important parts of my job from the point of view of the livelihood of Londoners."