Under-fire MPs Tom Brake and Paul Burstow have been accused of breaking pre-election promises by supporting controversial rises in university tuition fees.

Lib Dems, Mr Burstow, MP for Sutton and Cheam, and Mr Brake, MP for Carshalton and Wallington, both said they will not be voting against the coaliton Government's plans to treble tuition fees to up to £9,000 a year in today's crucial vote in parliament.

But in the run-up to May's general election, they campaigned on a platform of no rises in tuition fees.

Angry voters have accused them of deliberately misleading the electorate in changing their stance.

Geoff Martin, from trade union Merton and Sutton TUC, said: "If they break that pledge they will be surrounded by the stench of rank political hypocrisy.

"We are watching them closely and will drag them kicking and screaming to publicly account for their actions if, as we expect, they vote with their Government to hammer future generations with massive education debts."

But this week both MPs told the Sutton Guardian promises they made prior to the election were on the basis of a Lib Dem not a coalition Government, and the change in policy was drawn up as part of the coalition agreement.

Mr Brake said he understood voters' concerns, but the proposals would leave an estimated 18,000 of the poorest students better off, and would see the threshold for paying back the fee's raised and were needed because of the state of the country's finances.

He also said alternative proposals made by student unions would leave poorer students worse off.

He said he had not yert made up his mind on whether he would abstain from voting, or vote for the higher education bill.

Mr Burstow, a Government minister, said he did not stand as a single issue candidate and after looking at the merits of the reforms within the context of the state of public finances, he had decided to vote in favour of them.

He added: "They are very much better than anything Labour or the Conservative Party would have delivered on their own in Government."

Full statement by Government care minister Paul Burstow on tution fees: "I understand the anxiety of many people about changes to the way in which university courses are paid for.

"But let’s look at the details. The Government is not implementing the Browne Review recommendations.

"It has developed its own set of proposals that in effect transform the post course tuition fee into a graduate contribution.

"And let’s be clear about exactly what these proposals are. Under the proposed system, one in four graduates will pay less than they do now, while those who earn the most will pay more.

"In future no one will have to pay up-front fees, and for the first time ever this will also include part time students.

"Finally, the proposals will also raise the threshold when people start paying their graduate contribution to £21,000, and unlike Labour’s £15,000 threshold, we will periodically uprate the threshold to keep pace with inflation.

"As a result graduates will pay less per month than they do now.

"I did not stand as a single issue candidate and as such I will not vote on this issue in isolation.

"I have taken into consideration the overall state of the public finances; the cost of maintaining the status quo; the merits or otherwise of any alternative HE reforms; and the merits of the HE reforms proposed by Vince Cable.

"Having weighed all these considerations I have decided to vote for the reforms. They are very much better than anything Labour or the Conservative Party would have delivered on their own in Government."