The government jet was placed at the disposal of a government minister so he could vote in the Dáil against holding three by-elections and then take a late- night flight to Brussels.
The €9,000 flight for junior minister Dara Calleary was sanctioned by the Department of the Taoiseach amid confusion over pairing arrangements for TDs.
Fine Gael leader Enda Kenny had called for the issuing of writs in three by-elections for Dublin South, Waterford and Donegal South-West on Wednesday, 29 September.
The government, including Calleary, voted against the plan and proposals to run the elections have been put back at least until next year.
Labour TD Joe Costello said: "We have seen some outrageous use of the jet and this type of inappropriate use could if anything become more common.
"This government, as it desperately tries to stay in power coming to the end of its term of office, will probably use the government jet a lot more to bring people back simply to vote and try and keep their numbers up. They should make a point of foregoing the use of the two jets until the end of the economic crisis."
Calleary said yesterday he was left with no alternative but to use the government jet as he was standing in for finance minister Brian Lenihan in Brussels early on Thursday morning for a meeting of the Council of Ministers.
He said commercial flights were not an option because of concerns over pairing arrangements in the Dáil. He said: "We could not [fly that way] because of the situation with the pairs. "You don't know what votes are going to be called and there could have been votes again on the Thursday," Calleary said.
"I don't pick the jet. I can't say I want one. It arose because of the situation regarding pairs and at one stage, I wasn't even sure if I was paired for Thursday. There could have been a vote on anything. If I had had a pair, we would have chosen a commercial flight."
Calleary's government jet flight had already caused controversy in his Mayo constituency after the Learjet had been spotted dropping him off in Knock.
After flying to Brussels following the Dáil vote, it was then used to bring Calleary to Co Mayo on 1 October.
The flying time was 190 minutes and with the hourly rate for the Learjet estimated at €2,900, the cost of the flight came to €9,164.
Asked about the trip by the Western People newspaper, he said he had used "the smaller one".
However, it has now emerged that Calleary took a separate flight to Brussels on Monday, 27 September on board the 'bigger' Gulfstream IV.
That journey, which lasted 190 minutes ended up costing the taxpayer close to €25,000 and also stopped off in Knock.
Calleary said it would not have been feasible for him to remain in Brussels for the entire week and that the combined €34,000 government jet bill was necessary.
He attended an EU meeting on high-level financial reform from 6pm to 10pm on Monday and had another important launch in Dublin on Tuesday.