Boris Johnson has officially taken over as London mayor.

Mr Johnson was handed the seals of office by his predecessor Ken Livingstone and took over the role at midnight.

Speaking yesterday at the Sikh New Year festival, Vaisakhi, in central London, Mr Johnson said the hard work would now begin.

Mr Johnson has pledged to tackle violent crime, work to unite communities, make public transport safer and protect taxpayers' money.

"The last few days have been very, very exciting and very, very exhausting, but this is the single most wonderful job in British politics.

"I am going to be a mayor for all London and work to unite communities.

"One of the wonderful things we have got in London is fantastic diversity - we have got the whole world in a city.

"I certainly think it's extremely important that we get to grips with violent crime, which is going up, and we get to grips immediately with the scourge of so-called minor crime and disorder on the buses and the places in which the mayor is directly responsible.

"I am not pretending we can transform this overnight, but it is the job of the mayor to give a lead, and I won't rest till we have started to make a difference."

Mr Johnson's aides said his first days would be spent working to get 440 police community support officers on the Tube and trains, weapons scanners at stations and review plans to extend the congestion zone west.