国际英语新闻:News Analysis: Mysterious death squad could complicate political crisis in Bangkok

"Obviously, they have been trained for this mission and could possibly have a back-up squad," he said.

Kacha said he had an idea who the members of this mysterious squad are but declined to elaborate. He has, however, expressed his frustration over the orders from the government's Center for Maintaining of Peace and Order for the police to never use force against the protesters only to have his men killed or injured.

Department of Special Investigation Director General Tarit Pengdit said that the protesters had obviously allowed members of the mysterious squad to mingle with the crowd at the height of tension when they were confronting policemen in the streets.

In an earlier instance, a few military officers were arrested at a police checkpoint near Government House with guns hidden in a pickup truck with fake registration plate.

While the soldiers and their superior officer categorically denied that they had been hired as guards for the protesters, the police seriously doubted that.

National Security Council Secretary General Paradorn Pattanatabut said that authorities are worried that a "third force" could have entered the melee to trigger further bloodshed and then point the finger at the caretaker government.

Some observers said that the entry of the mysterious armed squad is not without precedent in the Thai history of political unrests.

Four years ago, a mysterious group called "men in black" threw grenades at army soldiers, killing a colonel and seriously wounding a division commander and dozens more troops and protesters near Democracy Monument.

The members of the mysterious squad swiftly left the scene after the attack and disappeared in the dark.

The incident, which occurred at the height of Red Shirt protests, triggered the massive Army crackdown on the protesters leaving nearly 100 people dead and about 2,000 others injured in Rajprasong and nearby areas.