Thailand said Tuesday that it was unable to find any other country willing to accept about 2,000 Rohingya refugees from neighbouring Myanmar who have been detained for several months.
"There is no third country ready to take them," foreign ministry spokesman Manasvi Srisodapol told AFP. "They are worried that if they receive one group, tens or hundreds of thousands of others will follow."
Many of the asylum-seekers have been locked up in crowded detention centres in Thailand for several months, prompting rights groups to call for their release.
Manasvi said the government was aware of the crowded conditions in the centres.
"Thai government agencies are currently discussing ways and solutions to improve their conditions," he added.
Since Buddhist-Muslim tensions exploded a year ago in the state of Rakhine in western Myanmar, thousands of Muslim Rohingya boat people -- including women and children -- have joined an exodus from the former junta-ruled country.
Those who arrived in neighbouring Thailand have been "helped on" by the Thai navy towards Malaysia -- their destination of choice -- or detained as illegal immigrants.
Thailand initially said the asylum-seekers would be allowed to stay for six months while the government worked with the UN refugee agency UNHCR to try to find other countries willing to accept them.
Manasvi suggested they might stay longer, describing the timeframe as "hypothetical".
UNHCR spokeswoman Vivian Tan said the ideal situation would be for peace to return to Rakhine so that the refugees could return home, but admitted that was unlikely to happen soon.
She said the crowded conditions at the Thai detention centres were not ideal but authorities were "trying their best to cope with this influx of people".
Rights groups have voiced concern that the Rohingya men have been separated from their wives and children -- who are held in separate community shelters -- and are not allowed to go outside unless they require hospital treatment.