BANGKOK, May 24 -- Chinese Ambassador to Thailand Ning Fukui said Sunday that responsible agencies of China and Thailand should strengthen punishment for travel agencies that continue to organize zero-fare tours despite complaints, including by blacklisting them.

China and Thailand have taken some measures to resolve the issue of zero-fare tours, which have proved effective to a certain extent, but failed to eradicate the practice, Ning said.

The practice of "zero- or negative-fare tours" refers to tour services sold by travel agents at or below cost in order to attract travelers, who are later forced to purchase goods or tip agents during their tours.

There have been frequent reports of Chinese tourists visiting Thailand being troubled by such practices.

The Chinese Embassy in Thailand has begun to forward a list of travel agencies, against which Chinese visitors have filed a lot of complaints, to Thailand's tourism departments, in hopes of deterring the practice by beefing up punishment for one or two of the agencies, according to the ambassador.