Chidchai was responding to a comment made by Democrat Party executive member Pichet Panvichartkul.

Chidchai said he had instructed the National Intelligence Agency (NIA) to investigate the allegations.

The agency had reported back to him that the charges were not true, he said.

"The NIA has met Prem and checked [on the allegation that his phone was tapped]. No such thing occurred,'' he told reporters.

Pichet insisted the allegation was true, saying the person who told

him of the alleged phone tapping was a respected senior figure whom he trusted.

He added that he was not claiming the alleged tapping was the work of a government agency, pointing out that such surveillance was so easy nowadays that many private companies were able to do it.

"They do not need to instruct major security agencies to do it. Nor do they need to do it at Ban Si Sao Thewet [Prem's residence] - they can tap mobile phones,'' Pichet said.

"We want to warn people who tap telephones not to do it because it's illegal,'' he said.

He said some groups had political motives for tapping telephones.

"They want to create mistrust among opposition parties and they want to restore confidence in their party members so that even if they receive less than half

[the vote] they can find alliances to form a government,'' he said.