MP Julia Drown will be sent a £12,000 mock bill from students at Oxford University in protest at government plans for bigger tuition fees.

The students have announced plans to invoice all Labour MPs who enjoyed a free education at the time they completed their Oxford degrees.

The move comes as MPs prepare to vote on controversial proposals to allow universities to charge annual fees of up to £3,000, from 2006.

The South Swindon MP - who studied politics and economics during four years at Oxford between 1981 and 1985 - will get a £12,000 bill, with an earnings-linked repayment schedule.

Tony Blair is also among the 45 Labour MPs being targeted by Oxford's students' union. More than 50 Oxford dons will also be sent bills.

Ms Drown today defended the Government's plans, saying they were necessary to allow more people to go to university.

She said: "I don't support the system that was in place when I went to university, because only a small proportion of people had the opportunity to go. It would be great if everyone in higher and further education could be given grants, but that would require higher taxes.

"And the polls show people are not prepared to pay that."

Under the plans, upfront fees of £1,100 will be scrapped and replaced by fees of up to £3,000, to be repaid after university by those earning more than £15,000.

John Little, the Oxbridge co-ordinator at New College, said the threat of a debt burden was not yet putting students off university, but predicted it could in the future.

He said: "If this plan goes ahead you could be looking at a situation where two students get married in their final year at university and find they have a combined debt of £60,000.

"I don't know how you could get a mortgage with a debt like that, and once such horror stories start filtering down to A-level pupils they may think twice about going to university, which is not the case at the moment."

Roshni Patel of New College's students union, said: "Most people are not really talking about tuition fees, it is just accepted.

"With my student loans I could get by if I had to pay £1,100 a year but it would be a lot more difficult if I had to pay £3,000 a year."

The Government faces an uphill fight to force through the changes, with 83 Labour MPs having pledged to oppose them.