Banda Aceh – Rebels in Indonesia's Aceh accused the military on Tuesday of executing a local television reporter who was found shot dead in the troubled province following a clash between separatists and marines.

The body of reporter Ersa Siregar from the private RCTI broadcaster was found on Monday, six months after he was kidnapped by separatist Free Aceh Movement rebels (GAM).

The rebel claim prompted an angry response from the country's chief security minister who accused GAM of using the reporter as a human shield. Military officials said the armed forces were investigating. One insisted troops did not know the rebels had Siregar with them.

The fate of RCTI cameraman Ferry Santoro, taken with Siregar, remains unknown, although troops later found his identity card at the location of Monday's firefight.

"The military killed Ersa Siregar in a raid in East Aceh. He was shot in the chest and neck," GAM spokesman Sofyan Dawood told Reuters by telephone, without specifying how he obtained the information.

"A few days ago he had also been shot in the leg. Siregar, who could not run for safety due to a wound in his leg, was executed by close-range shots." Colonel Ditya Sudarsono, spokesman for the martial law administration in Aceh, said Siregar's body had been flown to Jakarta for an autopsy.

"Clearly at that time there was crossfire. Whether he was shot by the military or by GAM we're still investigating," he said in response to the rebel accusation.

However, chief security minister Susilo Bambang Yudhoyono said the rebels had used Siregar as a shield. "Humans are being used as shields like that by GAM and they don't have any remorse about it. The world should see it that way," he said.

The killing prompted the New York-based Committee to Protect Journalists to call for a full investigation.

After abducting Siregar, the rebels initially said he was thought to be working for the military, a claim they later dropped. However, efforts to negotiate a release failed.

Government forces launched an offensive and imposed martial law in the province on the northern tip of Sumatra island soon after peace talks collapsed in May.

In June, the body of an employee with state broadcaster TVRI was found in a river in the province.

The military says it has killed or captured about 2,000 GAM members in the offensive – a statement difficult to verify because of travel curbs on the media and others in Aceh. GAM has fought for independence for the gas-rich province since 1976.

US-based Human Rights Watch said in a report this month that Indonesia's military was waging an extensive campaign of extra-judicial killings, kidnapping and torture in Aceh. The government has called the report "ill-informed and one-sided".