With Johnson and foreign minister Hunt stepping up their campaigns to replace Theresa May, both are seeking to raise money to pay for the cost of hiring venues, transport, staffing costs, leaflets and advertising.

Johnson has registered 235,000 pounds ($295,583) in the last two weeks, taking the total amount he has received in the last year to 502,000 pounds, according to new figures released by parliament.

The most recent donations include 50,000 pounds from Peter Cruddas, one of the City of London's most prominent Brexiteers, and 50,000 pounds from James Reuben, a financier.

By comparison, Hunt has registered no additional donations in the last two weeks.