London Mayoral candidates Zac Goldsmith and Sadiq Khan argued their visions of new homes in the capital during a debate on the Housing Bill going through Parliament.

The Government is proposing to extend the right-to-buy to housing association tenants, with a pledge to replace every social home bought with an affordable one.

January 7: Labour Mayoral candidate Sadiq Khan calls for "first dibs" for Londoners on new homes

January 5: Zac Goldsmith accuses London Mayoral rival Sadiq Khan of "playing the race card" in BBC Radio 4 interview

December 22: London Mayor hopeful Zac Goldsmith on juggling politics with family life, Crossrail 2 and not freezing rail fares

It would also introduce a new definition of affordable homes to be any property up to £450,000 within the capital.

The Labour Party has warned that more than 190,000 council homes could be lost should the bill come into place.

Mr Khan and Mr Goldsmith both introduced amendments; Mr Khan wants money from the sale of properties in London to be ringfenced and spent in capital, while Mr Goldsmith wants to pledge a two for one deal, where two affordable homes are built for every one housing association property sold.

Mr Khan congratulated Mr Goldsmith on the birth of his son, before warning members of the public should not be taken in by his "spin" and that there was no guarantee homes bought through right-to-buy in London would directly finance more homes in the same area.

He said: "Do not allow them to pull the wool over your eyes.

"My amendment will ringfence the money for new affordable homes in London.

"In few people's eyes are homes worth £450,000 affordable."

Mr Khan attacked Mr Goldsmith for his comments made in an article to the Camden New Journal about affordable housing.

In the article, Mr Goldsmith said the term affordable had become "elastic and misleading" and that "affordable has become a stick that people lean on but for many people its meaningless."

Mr Khan also criticised Prime Minister David Cameron over his response to the phrase "affordable".

He said: "The response to those who dared to suggest that this [£450,000] was not affordable was remarkable.

"He said people get so hung up on these definitions.

"The Prime Minister said the definition of affordable is a house that someone can afford to buy or rent.

"On that measure, a £26.2m mansion in Holland Park is affordable because someone could buy it."

Mr Khan added that his Conservative opponent was "far from the reality" of the housing problems in London.

Mr Goldsmith said: "The average price for first time buyers in London is more than £400,000.

"No one can argue that Londoners are [not] being priced out of their own city.

"It jeopardises London's economy.

"The bottom line is that we have to build more, and for people along the whole spectrum."

Mr Goldsmith praised a 'London version' of the help-to-buy scheme, introduced after the original failed to gather momentum, because "prices are so out of kilter" with the rest of the country.

He challenged Mr Khan to find out how London authorities would plan for the new homes to replace sold properties.

He said: "G15 [an organisation that represents London's 15 biggest housing authorities] has committed to delivering one-for-one replacements.

"They have told me they could deliver a lot more.

"They could replace each home with two provided there are flexibilities and access to public land."

Mr Goldsmith defended the right-to-buy extension to housing associations as the "right policy".