BANGKOK - Anti-government protesters seized an army tank deployed to enforce a state of emergency in the Thai capital Bangkok and may have taken others, a police spokesman told AFP on Sunday.

"The protest has spread to many parts of Bangkok. Protesters have seized tanks and armored cars," Major General Suporn Phansua, spokesman for Bangkok Metropolitan Police, told AFP.

He added they were still tallying up how many had been taken.

Minutes earlier protest leader Hweng Tojirakarn announced to demonstrators massed outside government offices that the group had taken two tanks and one armored car in the heart of Bangkok's shopping district.

Armed troops had fanned out across the capital after Prime Minister Abhisit Vejjajiva invoked a state of emergency to deal with escalating anti-government protests.

In another violent incident, protesters armed with sticks and paving slabs smashed a car they mistakenly thought was carrying the prime minister.

The incidents followed the arrest earlier Sunday of the leader of activists loyal to ousted former premier Thaksin Shinawatra who stormed an Asian summit on Thailand's coast on Saturday, forcing it to be cancelled.