Prime Minister Dr Mahathir Mohamad has challenged Najib Abdul Razak to furnish evidence that one of his aides had collected RM10 million in cash from the latter's residence before the 2013 general election.

"Show evidence, ask him to show evidence," he said at the sidelines of an event in Kuala Lumpur today.

In an exclusive interview with Malaysiakini yesterday, Najib, in explaining why he kept cash for BN's campaign expenses, had alleged that "one of Mahathir's people" had collected RM10 million in cash from him for the 13th general election.