Indonesian authorities on Wednesday raised to 1,407 the number of deaths caused by the 7.5 magnitude earthquake and subsequent tsunami that struck Sulawesi Island.

In a televised press conference in Jakarta, National Agency for Disaster Management spokesperson Sutopo Purwo Nugroho said the figure was expected to continue rising as search and rescue operations were underway with more rescuers and equipment joining in the mission.

Most deaths were recorded in Palu, the worst affected city on Sulawesi Island, while the rest of the casualties were in the neighbouring Donggala district and parts of Sigi and Parigi Moutong, Sutopo said.

An estimated 2.4 million people were affected by the twin disasters. A total of 70,821 people fled their homes and took shelter in camps or under tarpaulins in 141 spots. So far, not all of the basic needs have been provided, Sutopo was cited as saying by Efe news.

The number of people admitted to hospitals went up to 2,549 and those missing to 113. About 65,733 houses were damaged or destroyed.

The catastrophe began on Friday with a 6.1 magnitude earthquake that killed one person. It was followed by the 7.5 magnitude earthquake and then a tsunami.

Sutopo said that 63 per cent of Indonesians in the Sulawesi region hit by the quake and tsunami failed to hear the warning sirens.

Indonesian President Joko Widodo on Wednesday made his second visit to the devastated areas in Palu and Donggala. He later tweeted that a rapid response was the most important thing after the tragedy.

Widodo said that aid had started arriving and that US President Donald Trump had called him to offer assistance, state news agency Antara reported.

His visit came as electricity was being restored to around 30 per cent of Palu — a city of 350,000 inhabitants – Sarjan Mokodomgan, an employee of the state-owned electricity company, told Efe news.

Gasoline distribution began on Wednesday after at least a dozen tanker trunks arrived with fuel.

Indonesian authorities and various local and international organizations were working to bring humanitarian aid and medical assistance to those affected.

Meanwhile, the Soputan volcano located on the Sulawesi Island erupted on Wednesday, prompting authorities to raise the alert in the area to the second highest level.

Sotupan emitted a column of smoke and ash 4,000 metres high and authorities established a safety radius of 4 km around the crater.

Sotupan’s activity coincided with that of the Anak Krakatau volcano located in the Sunda Strait, between the islands of Sumatra and Java, which in recent weeks recorded dozens of eruptions.

Officials said that the condition of Anak Krakatau was safe, and beyond the safety perimeter established within a radius of 2 km around the crater.