Thailand's Center for the Resolution of Emergency Situation (CRES) warned "red-shirts" protestors camped in Bangkok's Ratchaprasong area that troops are waiting for an appropriate time to take back the area, the Center' s spokesman Col Sansern Kaewkamnerd said on Thursday.
Sansern urged innocent people to leave the rally site and return home.
Authorities will take decisive action against protestors when they disperse the mob, he said.
The "red-shirts" rally has started from March 12 as they are now gathering at the Rathchaprasong Intersection.
They have demanded Prime Minister Abhisit Vejjajiva to "immediately" dissolve the lower House of parliament and hold a new general election. The "red-shirts" on Thursday ruled out new talks with the Abhisit government.
According to Sansern, there were about 6,000 "red-shirts" at the site on Thursday morning, although the number was around 14,000 on Wednesday night.