Thai authorities have detained 11 men suspected of involvement in planning the assassination of Thai government's key figures and national sabotages, a senior police officer said on Monday.

Acting Provincial Police Region 5 Commander Pol Maj Gen Chaiya Siriamphankul said the 11 men were arrested in a resort in northern Chiang Mai's Mae On district and they are well-trained in using firearms.

Following the interrogation, the police had enough grounds that these 11 men had involved in a movement to destroy national security, assassin the very important persons and instigate disturbances in capital city of Bangkok and vicinity, Pol Maj Gen Chiya said.

The 11 people are now under a witness protection scheme to reveal more information to the authorities, said Pol Maj Gen Chaiya.

As for the rumor that these men were "red-shirt" militant or black-clad militant, Pol Maj Gen Chiya denied confirming the news saying detailed investigation needed to be done.

Chiang Mai "red shirt" key leader on Monday, however, denied the 11 suspects are members of the United Front for Democracy against Dictatorship (UDD), also known as "red-shirt" movement. Meanwhile, Puea Thai Party MP list and "red-shirt" core leader Jatuporn Prompan said those 11 men had nothing to do with Puea Thai Party and the UDD.

Combined force of police and security authorities in northern province of Chiangmai Saturday evening arrested those 11 men primarily alleged as "red-shirt" militant in a resort nestled in a mountain in Mae On district.