Bangkok, Sep 15 (IANS): Immigration police at land border crossings have now stopped giving entry stamps to foreigners who exit and immediately return to Thailand to extend their stay for 15-30 days on visa runs, media reported on Tuesday.

"The order is not new. Originally, officers were authorised to consider giving permits. But in this current situation of heightened security, all officers have to step up restrictions," said an official at the immigration bureau said.

Many foreigners regularly go on visa runs to Cambodia and return through the Sa Kaeo immigration checkpoint, the Bangkok Post quoted the official as saying.

"Some foreigners do not even go themselves, but get illegal networks to obtain the entry stamp for them," the official said, adding the government has cracked down on the border-run syndicates, prompting them to change tactics.

Law enforcement on these types of activities will intensify. From now on, foreigners who are re-entering Thailand will be screened rigorously.

They will need to provide information about their accommodation, tour company or other details to confirm they are in the country to travel as tourists.

The measure is likely to block scores of foreigners from re-entering Thailand through Sa Kaeo.

Those wishing to enter Thailand from Cambodia will have to go to Phnom Penh to apply for a visa at the Thai embassy.

The police investigation into the bomb blasts at Erawan shrine on August 17 and the Sathon pier on August 18 discovered immigration police were bribed by an illegal network linked to the perpetrators.