Bangkok - Nearly one-third of the Myanmar nationals who during the first six months of 2008 crossed to Thailand over the Friendship Bridge in Mae Sot border town failed to return home, media reports said Monday.

According to provincial immigration office figures 298,847 Burmese entered Mae Sot in Tak province during January to June, but some 86,517 went missing on the Thai side, said the Bangkok Post.

Tak immigration chief Police Colonel Tassawat Boonyawat said some of the Myanmar visitors may have returned to their homeland by other border crossings, but many others were working in Thailand illegally.

There are an estimated 1 million Myanmar nationals working in Thailand, which offers a limited number of work permits to migrant labourers from neighbouring countries.

"Illegal immigrants will remain an issue so long as the two countries differ economically and politically," noted Tassawat, who said Thai police lacked sufficient manpower to prevent the influx of illegal immigrants over the 500-kilometre Thai-Myanmar border. (dpa)