Forty percent of foreign men visiting the Philippines are sex tourists, the US ambassador to Manila said on Thursday.

Although Mr. Thomas lauded Philippine authorities' efforts against human trafficking, he stressed more had to be done. Asked for comments, Department of Tourism officials disputed Thomas's claims, saying they do not know where the US Ambassador got his statistics.

U.S. ambassador to the Philippines Harry Thomas made the remarks during a speech at a judicial conference on human trafficking.

Speaking before a forum of Filipino magistrates, Thomas challenged the legal profession to eliminate the "scourge."

"We know that 40 per cent of foreign men who come to the Philippines, including from the U.S., come for sexual tourism. That is not something I'm proud of. That's not something you should be proud of," Thomas said.

Thomas identified reported Manila hot spots for alleged sex trade, such as karaoke bars and clubs along Roxas Boulevard, a main road on which the US embassy is located.

"Corruption allows these notorious establishments to continue to operate. Local officials will look the other way or accept favours. These officials are doubly guilty," he said.

Thomas lauded Philippine authorities' efforts against human trafficking, but stressed more had to be done, and the US government would help in this endeavor.

"Any American caught engaged in any of these crimes or cybersex should be prosecuted to the full extent of the law and we will assist (you)," Thomas said he told Justice Secretary Leila de Lima.

He further said the successful prosecution of traffickers is not enough because eradicating trafficking "demands the traditional three P's: prevention, protection and prosecution."

Asked for comments, Department of Tourism officials disputed Thomas' claims.

"Certainly that is something we would like to dispute. We are not sure where his statistics are coming from," Tourism assistant secretary Domingo Enario told AFP.