Police take bomb hoax suspect Praphassorn Phornsurin, 30, to Tha Phra Police Station in Bangkok. He was released after questioning.

Metropolitan police yesterday received five more hoax bomb warnings despite threatening to jail prank callers for 18 months. One male caller was arrested but released later after claiming to have mental problems.

Five separate callers warned of bombs at Rajavinij School in Dusit district, the Bangkok Bank headquarters on Silom Road, Siam Square shopping centre, Victory Monument and the Anti Money-Laundering Office, said Pol Lt-General Viroj Chantharangsi, chief of the Metropolitan Police Office.

"Like yesterday, we found no bombs at any of the sites," he said.

"We also received another 28 calls reporting suspicious bomb-like objects in different places. None were bombs."

Viroj said the metropolitan police had received 150 bomb-related calls from December 31 until yesterday, of which 27 were bomb threats and the remainder to report suspicious objects.

Police yesterday arrested Praphassorn Phornsurin, 30, for calling the 191 hotline on Wednesday night with a warning about a bomb at The Mall superstore. He was caught at his home in Chomthong district along with the mobile used to make the call.

Praphassorn confessed to making the call, saying he was drunk and did it for fun and also because he is a supporter of former prime minister Thaksin Shinawatra.

"I personally dislike this government because it exiled Thaksin from the country as well as giving up all of Thaksin's good policies like the Bt30 health policy," Praphassorn said.

His mother, Sriprapha, burst into tears and asked the police to not jail Praphassorn. She told them he had had mental problems since undergoing serious convulsions at the age of six months and still needed daily medication.

"He is normally aggressive by nature - even to me, his parent. He must have called 191 because of his mental state," she said.

Police decided to release Praphassorn after taking his confession, but on the condition that his mental condition be confirmed later by specialists.

In Nonthaburi, a girl student of Sriboonyanond School was arrested yesterday for making a bomb threat at her school on Wednesday because she wanted it to close and let her go home early. Police later called the girl's parents with a warning about her bad behaviour and released her.

In Phitsanulok, local authorities have ordered regular security checks on the most important spots and shops after a spate of calls about bomb threats on Wednesday.

In Trang, a mysterious parcel was reported lying on the railway track yesterday.

However, police later found it was only a rock.