Ministers are considering a tax raid of up to £3bn on the gambling sector as Rachel Reeves casts around for funds to shore up the public finances.

Treasury officials are understood to be weighing up proposals, put forward by two influential thinktanks and backed by one of the party’s top five individual donors, to double some of the taxes levied on online casinos and bookmakers.

Measures could be included in this month’s budget, Labour’s first in 14 years, as the chancellor tries to plug the £22bn “black hole” that she claimed to have found in the nation’s finances after taking office.