The Thai military has acknowledged that army bullets were used in last week's attempted assassination of the founder of the so-called "yellow shirt" protest movement.

Thailand's army chief said Thursday that investigations showed that three of the bullets used in Friday's attack had been issued by the First Army Region to the Ninth Infantry.

Army commander General Anupong Paochinda said the bullets were distributed for shooting practice.  He said the army is still investigating how the bullets were leaked and will punish those responsible.

Anupong's comments follow speculation in Thai media that the military was involved in the attack on Sondhi Limthongkul.  A commentary in The Bangkok Post newspaper said only uniformed men with powerful political protection could have carried out such an attack with the capital under a state of emergency.

Sondhi remains in hospital recovering from surgery that removed bullet shards from his head. 

Gunmen wielding AK-47s and M-16s opened fire on his car in Bangkok last Friday, wounding Sondhi, his driver and an aide.  Police have not made any arrests in connection with the attack on the political figure and media moghul.

Sondhi is the founder of the People's Alliance for Democracy, which paralyzed the capital last year with protests and helped force a government loyal to ousted Prime Minister Thaksin Shinawatra out of power.

The alliance says the attack on Sondhi was politically motivated.  Thailand's Foreign Minister Kasit Piromya said earlier this week that Mr. Thaksin was behind the attack. 

Supporters of the fugitive former prime minister have targeted Kasit and called for him to step down because of his support of last year's protests against a pro-Thaksin government.

The assassination attempt follows violent clashes earlier this month between pro-Thaksin protesters and security forces that left two people dead and 100 injured.

Some information for this report was provided by AFP, AP and Reuters.