The head of the Council of National Security, General Sonthi Boonyaratglin, yesterday sent Singapore mixed signals even as the two allies squabbled over political sensitivity and national sovereignty.

Singapore has claimed it has the right to let ousted premier Thaksin Shinawatra meet with its deputy premier, S Jayakumar, while Thailand has accused the city-state of lacking discretion for doing so.

Sonthi told a forum that foreign ownership of the telecommunications industry could jeopardise national security.

"The armed forces are currently experiencing a problem. We pick up the phone, and the line runs to Singapore. We can talk about confidential official matters, but it goes to Singapore," he said.

"National security is an important matter for the nation, one that is entirely domestic," he said, adding that he did not see Singapore as a security threat, but rather a potential economic rival.

Sonthi stressed that the country's diplomatic slap against Singapore would not threaten military cooperation, perhaps the strongest in Southeast Asia.

Assoc Prof Panitan Wattanayagorn of Chulalongkorn University said the island republic depended greatly on Thailand for its military training. He pointed to the 20-year lease of the airbase in Udon Thani to the Singapore Air Force, as well as the joint and multinational military exercise that permits that country's military to conduct field training.

Prime Minister Surayud Chulanont said the government had weighed the pros and cons of the measures taken.

"The government has made its decision on the matter with careful consideration. So we are confident about what we have done and should not worry about the consequences," he said.

While falling short of bashing Singapore, Democrat Party leader Abhisit Vejjajiva lashed out at Thaksin.

He said he found it difficult to believe that Thaksin's conversation with Jayakumar was personal in nature.

"The discussion could not be 'How are you? I'm fine'," he said.

"Thaksin's private matters were always his business and for his business gains. As we know, his businesses have caused problems for Thailand, such as the sale of Shin Corp to Temasek of Singapore," he said.

"Even when he was prime minister and negotiated with foreign countries, he always took the opportunity to deal for his own benefit," he said.

But the Surayud government should not go overboard with retaliation, he said, adding that the two countries were both Asean members.

Abhisit asked the ousted premier to keep his word, as broadcast on CNN, that he would retire from politics.

"Instead of saying he has had enough of politics, Thaksin needs to state clearly that he will stop creating trouble for Thailand," he said.

In an interview with Singapore's Today newspaper, Kishore Mahbubanim, a former Singaporean ambassador to the UN, accused Thaksin of not being fair to Singapore.

The veteran diplomat, now dean of the Lee Kuan Yew School of Public Policy, said Singapore had become caught in the middle of another political struggle.

"In my experience, when that happens you get these strong positions being taken. It's a way for the government to protect itself. So, Singapore becomes a victim in these political wrangles," he was quoted by Today as saying.

Mahbubanim said Singapore had in the past gone through some rocky patches with the Philippines and Malaysia and suggested it should remain patient until the storm with Thailand blew over.

"When Thailand overcomes its difficult problems, its national interests will come into play. There are very sound reasons for Thailand and Singapore to cooperate."