The driver, Nuamthong Praiwan, said he painted the words "Destroy the country" on the side of his taxi, and the word "Suicide" on the trunk, before speeding into one of the tanks parked at the Royal Plaza.

"I did it intentionally to protest the junta that have destroyed our country, and I painted all the words by myself," he said from his bed.

Nuamthong suffered broken ribs and injuries to his chin and his eye.

A police however downplayed the incident, saying the driver was drunk and no message was sprayed on the taxi. "I didn't see any spray-painted words. Initially police suspected the driver might have fallen asleep, or it could have been reckless driving," police said.

The words painted on the car were however visible in photographs and television images of the taxi.

Taxi drivers are among the strong supporters of ousted prime minister Thaksin Shinawatra's populist policies.

The military deposed Thaksin last month while he was in New York.