Sadiq Khan has praised campaigns to bring Croydon into Zone 4, but stopped short of saying it should become a reality.

The Tooting Labour MP made the comments as he visited the borough's Gingerbread Corner nursery yesterday on the first stop of his London mayoral campaign.

Mr Khan also commended a bid by Labour-run Croydon Council to bring the Bakerloo Line into the borough, but said it was "too early to say" which areas would be best served by an extended service.

He was similarly cautious when discussing the Labour's new leader Jeremy Corbyn, but did indicate he would be prepared to challenge the party leadership in certain cases if he became mayor.

He said: "I may not have voted for him but it's important the party is united. But my job is to make sure I get the best deal for London - if they are saying things that are not conducive to London's well-being I will make my views loud and clear."

Mr Khan added: "Making our first stop in Croydon shows we're serious about next May. What we have seen in Croydon is a good example of what difference a Labour administration can make. They're not standing still.

"One of the great things about Croydon is the ambition of building work taking place, for the benefit of today's and tomorrow's residents."

If elected mayor, Mr Khan has promised that at least 50 per cent of housing in all new large developments would be affordable.

But in nearby Kingston, which has set that target for its large developments, provision is frequently well below the half-way level and councillors are sceptical it can be achieved.

As a parting shot, Mr Khan, who said he spent "a lot of time in Croydon", said he took a dim view of recent negative reports about the borough by French journalists covering the Rugby World Cup.

He added: "I think they're putting their excuses in already."