The assembly government want to bring in means-tested grants
Plaid Cymru's leadership has been defeated for the first time at a meeting of the party's national council over student top-up fees.
A motion was passed reaffirming the party's opposition to the fees in light of assembly government plans to abolish the current student subsidy.
Plaid fought the 2007 assembly election promising not to introduce top-up fees.
A motion to review this, put forward by the party's ministers in the coalition government with Labour, was defeated.
The party also used Saturday's meeting in Aberystwyth to call for any decision on a change of policy to be deferred until after the next assembly election so that all parties could put their views to the electorate.
Speaking to BBC Wales' Politics Show, Plaid chairman John Dixon confirmed that the party's leader Ieuan Wyn Jones had subsequently made a statement to the party's national council saying he would not be able to deliver the motion that was passed.
He said Mr Jones, who is deputy first minister in the Labour-Plaid government, made it clear he would not be able to persuade the cabinet to back Plaid policy.
Plaid Cymru chairman John Dixon said it would be naive to think there wouldn't be compromise with the party the junior partners in government
Mr Dixon said the issue was still up for discussion and denied that the position taken by the party's government ministers went against Plaid Cymru's constitution.
"There was a suggestion that we should look again at the policy concerned and I think we need to understand our ministers are in a very difficult position here," he said.
"There's a very tight financial settlement. They are between a rock and a hard place.
"But on this particular issue, what the party is saying is we understand the position you're in but the party wishes to continue to oppose tuition fees."
The One Wales agreement between Labour and Plaid Cymru says that current fee levels will be maintained until 2009/10.
Under proposals put out for consultation by Education Minister Jane Hutt, the current non-means tested student subsidy would be abolished the following year.
Currently, Welsh students who go to university in Wales receive a non-means tested grant of £1,890.
But under the minister's proposals this would be replaced by new means-tested grants.
Some of the money saved would be given to universities to help plug the £61m funding gap with England.
Mr Dixon attributed the differences of opinion within the party to the realities of coalition government.
He said that although this was the first time Plaid ministers found themselves at odds with party policy, it would not be the last.
Writing on his blog ahead of Saturday's meeting, Plaid MP Adam Price said: "The Labour party is entitled to their policy but they have no right to impose it unilaterally on us as this was not envisaged in One Wales.
"Plaid Cymru's national council... needs no reminding that it voted through One Wales to create the One Wales government. But this policy was never part of the deal."
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