"I took the working trip to study safety and security measures abroad with the aim of strengthening the existing system at Suvarnabhumi Airport," he said, about his week-long visit to the UK and Germany.

Saprang was reacting to claims on Monday from Thai Rak Thai executive Chamlong Krutkhuntode, who said the trip was a pretext to squander money on accompanying family members.

In his rebuttal, Saprang said his opponents from the former ruling party harboured grudges against him following the coup.

"I am a warrior who will not hesitate to repel any attacks," he said what he viewed as mudslinging.

He wanted to ask his opponents why they were trying to fault his trip while ignoring corruption scandals by the former government worth hundreds of billions of baht.

He said his trip was purely for business and not pleasure. And while some of the 13 delegates shared the same last name, they were responsible for specific duties to accomplish for the AOT.

"I don't think Bt7 million or the 13 delegates is the real issue, but the work my delegation accomplished."

He said his delegation studied many airport security models with a proven track record that could be readily applied to Suvarnabhumi.

He also dismissed speculation that he went to England in order to meet with ousted premier Thaksin Shinawatra, saying he had nothing to discuss with the deposed leader.

Constitution Drafting Assembly deputy chairman Seree Suwanphanont said Saprang should quickly dispel doubts on the true mission of the trip.

"It is understandable if AOT delegates attended to personal affairs after work but the trip must really be for business and not a pretext to travel at AOT expense," he said.

Seree said AOT board member and delegate Chirmsak Pinthong should justify why he took the expenses-paid side trip to Denmark and Norway, where his wife is Thai ambassador.