UK Prime Minister Boris Johnson has been given two weeks to explain to the London Assembly his links to internet entrepreneur Jennifer Arcuri, following claims relating to his time as London mayor.

The UK's Sunday Times newspaper claimed Johnson had a potential conflict of interest because Arcuri joined trade missions he led and also received thousands in sponsorship grants.

Johnson was London Mayor from 2008 to 2016. The claims in the newspaper relate to 2014 and 2015.

Len Duvall, chairman of the London Assembly oversight committee, wrote to Johnson saying: "I read with concern the allegations ... you failed to declare a potential conflict of interest in relation to the awarding of public funds to Jennifer Arcuri."

He then asked for "details and a timeline of all contact with Jenifer Arcuri during your period of office as Mayor of London, including personal, social and professional and an explanation of how that alleged personal relationship was disclosed and taken into account in any and all dealings with the GLA (Greater London Authority) and other parts of the GLA family."

Johnson has denied any wrongdoing, telling the BBC: "All I can say is, I am very proud of what we did as Mayor of London ... particularly banging the drum for our city and country around the world. I can tell you that absolutely everything was done entirely in the proper way."

Arcuri told the Sunday Times any grants she received and any trade missions she joined were "were purely in respect of my role as a legitimate businesswoman."

Duvall, who is from the opposition Labour Party, asked in his letter for Johnson to reply by 7 October.