The Liberals questioned why Dexter paid more than the premiers of New Brunswick and Prince Edward Island for round-trip tickets to China during a 10-day trade mission of Canadian premiers in September.
Liberal member Andrew Younger tabled government online expense claims in the legislature, showing Dexter's first-class ticket cost $7,136.
He compared that to records showing New Brunswick Premier David Alward paid $5,389, while P.E.I. Premier Robert Ghiz's ticket cost $3,762.
The P.E.I. premier's office later confirmed in an email that Ghiz flew economy class, while calls to officials in New Brunswick were not returned.
Dexter defended the cost, saying it's government policy that on extended flights of more than nine hours he would fly business class or an "upgraded class." He added that as head of the China trade mission, he needed proper rest to be alert for a heavy schedule of meetings.
"You are required to be able to, in very short order, get up and respond to all of those demands. I don't think that any of the taxpayers would find that unreasonable," he said.
Expenses for Dexter's trip to Israel in October 2011 show the premier paid $7,506.03 for his airfare.
Dexter said that cost was the result of changing his flight booking because his departure coincided with the federal shipbuilding announcement in Halifax, which he wanted to attend.
But Younger said he believes Dexter should have found cheaper flights during a time of government austerity.
"He's asked people to accept cuts and the premier seems to have no problem flying first class," he said.