Image caption Witnesses said lava and burning rocks were shooting from the volcano

Indonesia's Mount Merapi volcano has erupted again, with greater force than last week's eruptions in which 36 people died.

Witnesses said lava and burning rocks as well as hot ash were shooting from its crater for several hours.

An estimated 75,000 people have been evacuated from the area since Mount Merapi first erupted last Tuesday.

There was no immediate word on casualties. Officials have expanded the exclusion zone from 10km to 15km.

Local officials told the BBC's Indonesian service that funding for aid for refugees will run out in five days if a national disaster is not declared.

Civil servants in Magelang, one of the areas affected by the volcano, will have their pay cut to contribute to the cost of accommodating the refugees.

Workers will be asked to contribute between 25,000 rupiahs (£2) and 200,000 rupiahs on a voluntary basis, officials told the BBC.

Double disaster

The volcano, in central Java, spewed clouds of hot ash and gas some 5km (three miles) into the sky, eyewitnesses said.

The energy from the latest eruption was three times greater than that of the first one last week, government vulcanologist Surono said.

"We've decided to widen the danger zone to 15km, the refugee camps must be moved outside the zone," he told the AFP news agency.

There were reports of panic at some shelters.

"Hundreds of people fled in panic from the refugee shelter in Glagaharjo, 10km from the peak," aid worker Anwar told AFP.

"The refugees cried and screamed hysterically, and some fainted."

President Susilo Bambang Yudhoyono visited some of the shelters earlier on Wednesday, but it was not clear if he was still in the area when the latest eruption began.

Scientists are warning of further eruptions in the coming weeks.

Indonesia is also dealing with the aftermath of another natural disaster, after a tsunami hit the Mentawai islands last week, claiming more than 400 lives and sending thousands into emergency shelters.