The Tourism and Sports Ministry has investigated illegal tour companies offering extremely cheap packages, forcing 10 of them to close.

Tour agencies said these grey market companies already account for 50% of Chinese tour groups in Thailand.

The minister's action is in response to a call from the Association of Thai Travel Agents, which recently raised concerns about the return of ultra-cheap inbound packages. These packages promise very low fares to buyers, then once in Thailand they force tourists into shopping and spending at inflated prices.

Six governmental agencies set up a joint operational centre to crack down on tour businesses using nominees and offering lower-than-cost packages over the past six months.

After investigating 30 tour companies, the Tourism Department forced 10 companies to close.

Thai nationals determined to be nominees are banned from operating a tour business for five years and are subject to punishment including prison sentences for both Thais and foreigners.

The centre prosecuted 10 foreigners for illegally working as tour guides with these 10 companies, as this job is reserved for Thais.

If the Thai government wants to crack down on the large players, who are the same firms and individuals that conducted zero-dollar tours a decade ago, it might have to seek cooperation with Beijing, the Tourism Council of Thailand said.