Green Party leader John Gormley said tonight he was "greatly saddened" by Trevor Sargent's resignation.
"There is nobody in Leinster House - or in Irish politics generally - whom I admire more than Trevor. He has brought a unique mix of ability and talent, decency and honesty to Irish public life," Mr Gormley said.
"Trevor's departure is all the more difficult because he is more than just a colleague, he is a trusted friend and confidant," he said. "I note that in tendering his resignation he has acted promptly and without any self interest. That is totally in keeping with his approach to politics and the contribution he has made across the past four decades.
"Trevor will continue to serve the people of Dublin North as their TD with the same total dedication he has shown since June 1992. He will be missed from the Green Party team in Government, but he will continue to work closely with his parliamentary party colleagues."
The Taoiseach this evening said he had accepted Mr Sargent's resignation with the "utmost regret in the circumstances". Brian Cowen also said he believed his former minister's intention "was to act in good faith" as outlined in his Dáil statement.
He said the Green TD had been a "most constructive and positive member of Government," adding: "I know that Trevor vigorously pursued his responsibilities in the Department and can be satisfied that his time there has been very productive in furthering his objectives in that regard."
Mr Cowen also dismissed Opposition allegations of "dirty tricks" in relation to the revelations surrounding Mr Sargent as "beneath contempt". He said there was "an attempt to destabilise the Government . . . in the context of innuendo".
Minister for Agriculture Brendan Smith thanked Mr Sargent for the "very significant" contribution he had made since his appointment as minister for state.
"Trevor has, at all times, displayed great energy and commitment to his role . . . and was widely respected by the many stakeholders with whom he worked closely," Mr Smith said, adding he wished the Green TD every success in the future.
Fine Gael justice spokesman Charlie Flanagan said a series of "tit for tat political hits" were now affecting Government stability. He said these raised serious questions "in light of correspondence to gardaí being leaked which is clearly not by chance just four days after the resignation of a Fianna Fáil minister".
The Opposition frontbencher said the Minister for Justice now had questions to answer.
“Trevor Sargent showed the type of dignity today that was sadly lacking in the resignation of his Cabinet colleague, former Minister for Defence Willie O’Dea," Mr Flanagan said. "He [Mr Sargent] took the honourable course of action and resigned without hesitation once the matter became public."
Labour Party leader Eamon Gilmore said Mr Sargent "acted with dignity and honour" by tendering his resignation. However, Mr Gilmore said there were a number of questions that remain to be answered, not least on the timing of the leaking of the letters to the media.
"Are we to believe that it was purely coincidental that this followed so soon after the enforced resignation of Willie O'Dea last week?" he asked.
Mr Gilmore also demanded to know when the Department of Justice first became aware of Mr Sargent's correspondence with the garda.
"This is the second ministerial resignation to hit this Government with the space of five days," Mr Gilmore said. "Trust between the two parties in Government has clearly been destroyed and this is a Government that is holed below the waterline."
Sinn Féin TD Caoimhghín Ó Caoláin also contrasted the manner in which the two ministers resigned and said the Taoiseach should not go through the "charade" of a reshuffle:
"The former minister of state for food acknowledged that he acted wrongly and consequently resigned. Trevor Sargent has acted appropriately in stepping down. Minister O’Dea had to be dragged twice through the courts and through the Oireachtas before he was eventually forced to resign," Mr Ó Caoláin said.