Deputy Prime Minister for security affairs Suthep Thaugsuban said in a televised address around 11:30 p.m. that the grenades were fired from behind the King Rama VI statue where the "red- shirt" protesters were demonstrating.

He warned residents in the area to stay away more than 400 meters from the main road as the grenades have a range of 400 meters.

But the "red-shirts" leaders earlier denied that the "red- shirts" have any connection with the blasts.

Prime Minister Abhisit, Defense Minister Prawit Wongsuwan and Army Commander Anupong Paojinda are trying to return the situation to normal.

Security forces were enforced in the city but Suthep said it is not convenient for police and troops to enter the rally site to handle the emergency at night.

On Thursday evening, the Civil Court issued an injunction against the use of force to break up the "red-shirt" rally at the Rajprasong Intersection.

But the court noted that the demonstration affected the public so the government could use internationally-accepted measures to deal with the protesters from lighter to harsher measures.

Sansern Kaewkamnerd spokesman for the Centre for the Resolutions of Emergency Situations or CRES said in a telephone with TPBS TV that the army will not disperse the "red-shirt" protesters Thursday night.

Just an hour after the blasts, some 100 people clashed with the red-shirted protesters near Bangkok's main financial district.

The people wearing multi-colored shirts forced through the line of police to confront the red-shirted protesters at the nearby Lumpini Park around 10:45 p.m., a Xinhua reporter at the scene said. The two sides hurled bottles at each other and fired slingshots at each other.

This is the second day that the two sides clashed. On Wednesday night, the same group also hurled bottles and stones at the "reds- shirts" who camped near the Silom area for more than two weeks, leaving at least 20 injured, including two foreigners.

The anti-government "red-shirts started their protest rally in the capital a month ago, demanding Prime Minister Abhisit's resignation and dissolving the lower House of the parliament for new elections.

A damaged motorcycle is seen after an explosion on Silom Road in the financial district of central Bangkok,capital of Thailand,April 22,2010.[Shi Xianzhen/Xinhua]