The last hiker missing after a volcano eruption in Indonesia was found dead Wednesday, rescuers said, raising the death toll to 23 three days after the disaster.

Mount Marapi on the island of Sumatra in Indonesia's west spewed an ash tower 3,000 metres (9,800 feet) — taller than the volcano itself — into the sky on Sunday as 75 people hiked in the area.

Hundreds of rescuers have worked tirelessly to find the missing hikers, who have been carried down the mountain in bodybags in an arduous search effort hampered by further eruptions and bad weather that sometimes forced workers to take shelter.

"The joint search and rescue team has found one victim of the Mount Marapi eruption, who is now in the process of being evacuated," Abdul Malik, head of the Padang Search and Rescue Agency, told reporters on Wednesday evening.

Basarnas, the national search and rescue agency, earlier identified the final hiker as a woman.

It came after Suharyono, the West Sumatra police chief who like many Indonesians goes by one name, told reporters late on Tuesday that the last hiker was feared dead.

"23 people are suspected to have died. We all prayed they all could be rescued but there was nothing we could do, God and nature had made a decision," he said.

Marapi, which means "Mountain of Fire", was still billowing a column of smoke into the sky on Wednesday morning before another eruption just after midday local time (0500 GMT), an AFP journalist said.

Officials monitoring the volcano had also detected at least five further eruptions on Tuesday as the search went on.

'Some jumped'

Fifty-two people had been rescued since the eruption and some of the survivors have described their panic after it started.

"I was zig-zagging, going down around 30 to 40 metres" to a trekking post, Ridho, 22, told AFP from a bed in a nearby hospital.

"The eruption sounded loud, I took a look behind and then immediately ran away as everyone did. Some jumped and fell. I took cover behind the rocks, there were no trees there."

Suharyono said on Tuesday evening that two of the 75 hikers were police officers, one of whom survived. He suspected the other had been killed.

"They both just wanted to see the volcano, they were off duty," he said.

"One of them survived and had a broken arm, he is being treated by doctors. For the other one, we suspected he died. Let's wait for confirmation."

The head of Indonesia's volcanology agency, Hendra Gunawan, said Marapi has been at the second level of a four-tier alert system since 2011, and a three-kilometre exclusion zone had been imposed around its crater.

He appeared to blame hikers after the eruption for going too close to the crater, saying the agency recommended no activity in that area.

The official number of hikers given by officials was sourced to an online registration system but officials warned there could have been more on illegal routes.

"Maybe there were hikers who were not registered, and sometimes illegal hikers did not want to pay, they just climbed," said Suharyono.

Indonesia experiences frequent seismic and volcanic activity due to its position on the Pacific "Ring of Fire", where tectonic plates collide.

Marapi is the most active volcano on Sumatra and one of nearly 130 active volcanoes in the Indonesian archipelago.