BANGKOK, April 12 (Xinhua) -- Thai Prime Minister Abhisit Vejjajiva on Sunday declared a state of emergency over Bangkok and some districts in five nearby provinces, citing danger of escalating violence by anti-government protesters in the capital.

Besides Bangkok, the emergency decree also covers some districts in five provinces around Bangkok, including Nonthaburi, Samut Prakan, Pathum Thani, Nakhon Pathom and Ayutthaya.

Abhisit explained on TV that the emergency decree was not imposed earlier in Bangkok because the government wanted to keep the normal order in the capital, but situation became tense and the government had to impose the decree to restore normality.

He cited the acts of anti-government demonstrators, or known as "red-shirted" people, to obstruct the ASEAN and Related Summits as example of the tension incited by the protesters.

The summits, which involved 10 ASEAN countries and its six dialogue partner nations -- China, Japan, South Korea, India, Australia and, was scheduled April 10-12 for Saturday and Sunday in the central beach resort city Pattaya

The Thai government was forced to call off the meeting scheduled for Saturday and Sunday and send foreign leaders to depart Pattaya without formal talks Saturday afternoon after over 1,000 red-shirted protesters besieged and broke into the meeting venue, demanding the Abhisit government to resign.

The situation in Pattaya cooled down after protesters, led by United Front for Democracy against Dictatorship (UDD), declared victory over the cancellation of the summits and retreated back to Bangkok, where they set up their main rally venue at the Government House.

However, the atmosphere in Bangkok became tense after a UDD leader who led the protesters to block summits in Pattaya was arrested, which angered UDD supporters.

The declaration of state of emergency came several hours after the Thai PM on TV apologized to people over its failure to keep the protests under control at the Pattaya summits, and vowed to take tough measures to restore law and order in the country, including seeking arrest of protest leaders.

Abhisit tasked Deputy Prime Minister in charge of security matters Suthep Thaugsuban to be responsible for enforcing of the state of emergency measures.

By far no army top brass, who had played the key role in the Sept. 19 bloodless coup in 2006 overthrowing the former prime minister Thaksin Shinawatra, who the red-shirt people support, had came out to respond to the crisis.

On early Sunday afternoon after the declaration of emergency decree, there was a riot outside the Interior Ministry in Bangkok when at least several hundred red-shirted protesters tried to attack a motorcade leaving the compound as they suspected that Abhisit and Suthep was inside the cars. But the two was reportedly unharmed. The riot caused at least several injuries, including police and protesters, Thai state TV NBT reported.