Boris Johnson planned to set up a £100 million investment fund with a former model whose companies he is accused of having allowed to benefit from public money and privileged access.

He announced a fund to support technology companies in the Middle East at a summit organised by Jennifer Arcuri, an American entrepreneur who had just completed an MBA.

The London assembly has given Mr Johnson two weeks to provide details of all his social, personal and professional contact with Ms Arcuri and to confirm whether he disclosed their alleged relationship when he was the mayor of London.

The assembly’s oversight committee has the power to summon Mr Johnson to give evidence in person if he fails to respond to their request.

Mr Johnson,