Jun.28 (GMM) London mayor Boris Johnson on Thursday could not guarantee the British capital will be able to host Bernie Ecclestone's race.
F1 chief executive Ecclestone has said he is prepared to put up the money and promote a London street race.
Some immediately wrote off the plans as either a classic Ecclestone diversion or a publicity stunt.
But London mayor Johnson told the UK newspaper Express he is "broadly positive" about the plans.
"I am always interested in projects that attract jobs and bring growth," he said, insisting it will be important to find out if there is "a really good economic case" for the event.
Johnson added: "The question of air quality and noise impact will have to be looked at. I am broadly positive providing we can satisfy the air quality and noise issues."