The executive and council of the students' union in University College Dublin have both voted "no confidence" in the union's president, John Nisbet.

The votes come after a controversy over a forged letter, which purported to be from the education officer of the UCD union, Charles McConalogue. While Nisbet was in no way responsible for the letter, he has come under fire because he knew of the existence of the letter before McConalogue did - and failed to draw it to the attention of his colleague. In a separate development, the union's welfare officer (who was also union vice-president) has resigned - he too bore no responsibility for the letter.

The controversial letter, which was typed on unheaded notepaper and which bore the forged signature of McConalogue, purported to pass on information to the Minister for Education about a number of people who would be attending a USI protest about student welfare.

The letter was shown to a UCD college newspaper three weeks ago, and a journalist from the newspaper told McConalogue of the contents of the letter to get his reaction. McConalogue phoned the Garda and the letter is believed to have been brought to the attention of the Garda Fraud Squad.

It is believed gardai informed McConalogue that the matter was a civil rather than a criminal one, as there had been no attempt to defraud money. McConalogue is now reported to be considering launching a defamation action against the people he believes to be responsible for the letter.

Preliminary inquiries are also being made by the independent appeals board (IAB) of the union. The IAB features two member of UCD's academic staff with legal experience as well as the student services officer, the union's returning officer and a nominee of the union president. The union solicitor also sits on the IAB.

The union executive earlier promised to fund any independent legal advice McConalogue might wish to seek, subject to ongoing review.

McConalogue called on the union president to resign after the student council voted "no confidence" in him on Wednesday at the end of a four-hour meeting. "It's time for him to resign. It's clear that the bodies representative of UCD students haven't confidence in John or his presidency. "This is a serious matter for the union, and the president is making a grave mistake if he doesn't resign."

Nisbet admits he made a mistake in not revealing the existence of the letter to McConalogue sooner and says he wishes he had acted differently when he found out about the letter. However, he feels that there were "a lot of political motivations" at work in the "no confidence" votes by the union's executive and council.

"This is an error of judgment that has already been partly sorted out and will be sorted out further. Charlie needs to have justice done. I want to continue working on the big picture. For me it will be a case of restoring confidence in my presidency. I don't think impeachment procedures will be initiated, but if they are I'll fight them every step of the way." If impeachment proceedings were initiated this week, then it is possible Nisbet would face a referendum on his presidency at the same time as the sabbatical elections in UCD. Nisbet believes, he says, that the council will be happy with the "rap on the knuckles" it delivered on Wednesday night and says he has already had promises of co-operation from people who voted "no confidence" in him.