JAKARTA, Indonesia | Wed Oct 27, 2010 10:35am EDT

JAKARTA, Indonesia (Reuters) - A tsunami and a volcanic eruption in Indonesia have killed more than 300 people with over 400 missing and tens of thousands displaced, authorities said on Wednesday.

One of Indonesia's most active volcanoes spewed out clouds of ash and jets of searing gas in an eruption that has killed at least 28 people and injured 14.

Mount Merapi, on the outskirts of the city of Yogyakarta on Java island, first erupted on Tuesday, a day after a tsunami pounded remote islands in western Indonesia. The death toll in the tsunami was at least 282, said West Sumatra provincial disaster official Ade Edward.

The tsunami, triggered by a 7.5 magnitude quake that struck 78 km west of South Pagai, one of the Mentawai islands, flattened several villages and a surf resort. At least 411 people are still missing, Edward said.

The National Disaster Mitigation Agency said on its website that 4,000 people had been displaced by the tsunami.

Metro TV showed footage of villages flattened by the wave, with dejected survivors combing through rubble for belongings.

Authorities have been battling to handle both disasters, with more than 40,000 villagers evacuated from the slopes of Mount Merapi, where many houses have been destroyed, their ruins lying covered in white ash.

Kresno Heru Nugroho, head spokesman for Yogyakarta's Sardjito hospital, said 28 people had been killed by deadly bursts of hot air released by the volcano late on Tuesday. His colleague Endita Sri Andrianti said some were burned beyond recognition.

VOLCANO SPIRITUAL GUARDIAN FEARED DEAD

Another hospital official told Reuters it was likely that among the dead was the elderly spiritual guardian of the mountain, Mbah Maridjan, believed by many Javanese to possess magical powers. Tests were being carried out to confirm a charred body found on the volcano was his.

Many Indonesians posted tributes via Facebook and Twitter to the volcano's widely-loved custodian, regarded as a protector who used a combination of Islamic and animist rituals to keep Merapi under control.

The Sultan of Yogyakarta also appeared on Metro TV to pay tribute to the guardian.

Many of the victims had been found in or around Maridjan's house in the village of Kinahredjo, close to the volcano's crater, local media reported. A Reuters cameraman at Kinahredjo said that several houses and cattle had been burned.

"All the houses are blanketed in ash, completely white. The leaves have been burned off the trees," said cameraman Johan Purnomo.

The country's top vulcanologist, Surono, said Merapi was now "quite calm" but that the respite could be temporary.

"I have advised local officials to continue the evacuations. It's still on the highest alert level," he said.

Metro TV, however, showed some villagers returning home on Wednesday.

Indonesian President Susilo Bambang Yudhoyono flew back from Hanoi, where he had been due to take part in a summit of Asian leaders, to oversee relief efforts for the Merapi eruption and Sumatra tsunami. He said he expected to return to Vietnam for the main summit which runs from Thursday to Saturday.

In a 1994 eruption after the volcano's lava dome collapsed, 70 people were killed. The volcano killed 1,300 people in 1930.

In December 2004, a tsunami caused by an earthquake of more than 9 magnitude off Sumatra killed more than 226,000 people. It was the deadliest tsunami on record.

(Additional reporting by Beawiharta; Editing by Ron Popeski)