A senior adviser to the London mayor faces further questions about the way he used a corporate credit card.

Ian Clement stood down as Boris Johnson's deputy mayor for external relations on Monday after a number of discrepancies were discovered in the way he used his credit card.

The Assembly's business management and administration committee is set to question policy and planning deputy mayor Sir Simon Milton and Greater London Authority (GLA) executive director of resources Martin Clarke about the expenses claims today.

Committee chairman Jennette Arnold warned that Clement's resignation did not excuse him from facing further questions about his spending.

"Ian Clement's repeated misuse of his City Hall credit card was clearly a serious breach of Greater London Authority rules for which he has answered with his job," she said.

"However, Mr Clement's resignation cannot be considered an end to the matter.

"Serious questions remain about how long the misuse of the card continued, apparently undetected, and the type of expenditure that was charged to the GLA without being repaid."

Clement was reprimanded last week for using his credit card to buy £2,300 worth of personal items, including groceries and a meal in New York.

An internal GLA investigation found that he had repaid the money at the earliest opportunity and made no personal gain.

But the former leaader of Bexley Council was asked to step down on Monday after three Conservative councillors denied that they had been present at meals that Clement claimed he had paid for.