Jakarta – The Indonesian minister who said he was personally supervising a treasure hunt to raise money for the state has been forced to tender a public apology and may be investigated for violating a law which carries a 10-year jail term.

The police are questioning witnesses to gather evidence to summon Minister of Religious Affairs Said Aqil Husein Al Munawar who ordered the excavation of an archaeological site associated with the 16th Pajajaran Kingdom.

Bogor police in West Java have questioned seven witnesses, including four diggers and an employee with the West Java and Banten historical heritage conservation office.

A police source said the dig was a civil offence because it violated a law on cultural sanctuary. It carries a maximum sentence of 10 years in jail.

The minister – who claimed a "wise man" had tipped him off about the treasure, had said it could be used to repay the country's foreign debt. He had said the excavation had the approval of President Megawati Sukarnoputri but her aide Pramono Anung has since contradicted this.

His statments raised a flurry of criticism from several legislators and sociologists who said the move showed the government's inability to find solutions to complex problems facing the country.

The Indonesian Ulamas Council, the country's highest Islamic body, also condemned the excavation and called on the government not to rely on "irrational things" in managing the country.

During his visit to the North Sumatra capital of Medan on Monday evening, Mr Said Aqil apologised to the Sunda community for the excavation.

"I apologise if the public feels offended for the lack of coordination in the excavation. I have no political interest at stake at all," said. "I did not intend to harm the historical site, but to follow up on information a cleric gave me," he said.