James Couchman said he and other MPs had witnessed "a balletic coupling by two young people" and had been "assailed on all sides by very young hostesses".
The Gillingham MP - who stressed his distaste for what he had witnessed - was speaking in support of the Sexual Offences (Conspiracy and Incitement) Bill which aims to crack down on organisers of sex tours used by British paedophiles to go on holiday in third world countries for sex with child prostitutes.
He recalled that he had been a member of an Inter-Parliamentary Union delegation to Thailand and Indonesia in 1989.
"It was our experience that the Thai authorities, far from wanting to discourage this sort of activity at that time, were turning a Nelson eye on the whole procedure," he said.
Mr Couchman said the delegation had a very busy week which included visits to Cambodian refugee camps and meeting "countless politicians and generals".
"But it was held that our education about Thailand would not be complete without a visit to the district of Pat Pong - and it is a very appropriate name for this district.
"We were told that we should go and view some of the clubs in Pat Pong and that is precisely what we did. We were greeted in this rather unsavoury and seedy area of Bangkok by all sorts of touts offering all sorts of services, but principally trying to sell the clubs by which they were employed.
"We went to one club and the first thing that we were met by was what I can only really describe as a balletic coupling by two young people and a large audience who were enjoying this particular spectacle. And from there it was downhill all the way."
The Bill, proposed by John Marshall, Tory MP for Hendon South, gained an unopposed Second Reading and is now virtually certain to become law.
The Bill would make it an offence - with maximum life sentences - to incite people to commit sexual offences against children abroad. But it will not eradicate sex tourism.
The Government reacted coolly to calls for it to go further and take swift action to ensure so-called "sex tourists" could be prosecuted here for crimes against children committed abroad.
Tom Sackville, a junior Home Office minister, said there would be "considerable practical difficulties involved" in mounting prosecutions in the UK for offences committed abroad. "There are doubts as to whether extra-territorial jurisdiction would be likely to be of assistance in bringing to justice British nationals who commit offences against children in other countries," he added.Reuse content