Jakarta: Indonesia's deputy energy minister, a key policy maker in the government's drive to tighten mining regulations, died after he collapsed while hiking on Saturday, a spokesman said.

"The president has been informed by the energy and minerals minister... that his deputy minister Widjajono Partowidagdo (has) passed away," a presidential spokesman told a news agency.

The cause of his death is unknown.

Partowidagdo was central to a looming government decision on whether to tax the export of most raw minerals ahead of a blanket ban proposed for 2014.

The proposal is one of a series of regulations aimed at bringing more benefits of the country's natural resource wealth to Indonesian people.

Partowidagdo left for the hike on Friday and collapsed on Saturday at around 1 pm (0500 GMT) as he was climbing the 2,800-metre Mount Tambora volcano on Sumbawa Island, just east of the tourist islands Bali and Lombok.

A search and rescue helicopter team was delayed by heavy fog and managed to recover Partowidagdo's body only by late afternoon.

His wife Ninasapti Tri Aswati said that rescuers had called her after receiving reports he had collapsed.

"He was generally in very good health. Rescuers called me and said he complained (that he) couldn't breathe, that there was not enough oxygen," she told TV channel.

 (Agencies)