The opposition Labour candidate for London Mayor said on Tuesday he would look to pension funds to help fund a new wave of rail and home building to cater for a booming population in Britain's capital if he wins a May 3 election.

Race underdog Ken Livingstone, who was London Mayor between 2000 and 2008, said he would have a good chance of unlocking the kind of investment the city needs to prepare for the future.

I will be saying to pension funds, invest in building homes in London ... or invest in building Crossrail 2 or 3, he told reporters at an event in parliament.

Livingstone is standing against incumbent Conservative London Mayor Boris Johnson. Opinion polls have consistently shown Johnson as frontrunner.

Work is already under way across London to build Crossrail - linking commuter towns east and west of the city as well as the Canary Wharf business district and Heathrow airport - by 2018 and at a price of about 15 billion pounds.

Livingstone wants to see similar links between the south and north, across the river Thames.

He also believes London needs hundreds of thousands of new homes to house a population which is expecting to hit nine million within the next decade.

A city like this needs to be planned a decade or two decades in advance, he said.

(Reporting by Matt Falloon)