Tories resent Britain's £4.4bn share of the bill

George Osborne faced a Tory backlash last night after it emerged that Britain could contribute up to £4.4bn towards a Portuguese rescue package.

The Chancellor will join fellow finance ministers today in Budapest to discuss the latest crisis to hit the eurozone. A deal signed by his Labour predecessor, Alistair Darling, commits Britain to contributing a share of any bailout loan.

But the Conservative leader in Brussels, Martin Callanan, said: "Voters will not accept that at home we are making tough, but fair, savings only to send money to countries that should never have been allowed to join the eurozone in the first place." The Eurosceptic MP Bill Cash, the chairman of the Commons European Scrutiny Committee, insisted there was no legal basis for a contribution. He said: "In these times of austerity, the eurozone should look after itself without any British contribution."

The Chancellor said the crisis underlined the case for austerity measures in Britain: "Those in our country who deny the urgent need to deal with our deficit are playing Russian roulette with Britain's national sovereignty."