Boris Johnson has responded to City Hall’s questions over his relationship with Jennifer Arcuri, amid allegations of a conflict of interest – but the body says it is “not able to publish it”.

The London Assembly had given the prime minister 14 days to answer its questions over allegations the businesswoman received favourable treatment while he was London mayor.

Johnson responded on Tuesday evening as he faces continued calls for clarity over allegations Arcuri was given public funding and privileged access to three foreign trade missions while Johnson was mayor.

The assembly had asked him to provide details and a timeline of all contact with Arcuri while he was the mayor.

It also asked him to give an explanation of how that relationship was disclosed and taken into account in all dealings with the assembly and related bodies.

Despite his response, there was a spat between City Hall and those close to Johnson over the deadline.

City Hall initially criticised him for missing the 6pm limit, with oversight committee chairman Len Duvall warning the PM the situation has “now become grave”.

A Tory source hit back saying it was missed because “it was an invented City Hall deadline that they have never said to us”, and criticised London Assembly “grandstanding” and Duvall for “playing politics”.

But the PM’s response was received about an hour after the deadline. A tweet from the London Assembly said We have now received a response on behalf of Boris Johnson. We are not able to publish it.”