JAKARTA • Indonesia's geophysics agency lifted a tsunami warning 34 minutes after it was first issued following a major earthquake that sent huge waves crashing into the north-eastern coast of Sulawesi island, killing hundreds and leaving thousands more homeless.

The 7.4-magnitude earthquake and tsunami, which hit the city of Palu and further along the coastline, killed more than 1,200 people.

Hundreds of people had gathered for a festival on the beach in Palu last Friday when waves as high as 6m smashed onshore at dusk, sweeping many to their deaths.

BMKG, the meteorology, climatology and geophysics agency, faced criticism on Saturday on social media, with many questioning if the tsunami warning was lifted too soon. The agency said it followed standard operating procedure and made the call to "end" the warning based on data available from the closest tidal sensor, around 200km from Palu.

"We have no observation data in Palu. So we had to use the data we had and make a call based on that," said Mr Rahmat Triyono, head of the earthquakes and tsunami centre at BMKG.

He said that the closest tide gauge, which measures changes in sea level, recorded only an "insignificant" 6cm wave and did not account for the giant waves near Palu.

"If we had a tide gauge or proper data in Palu, of course it would have been better. This is something we must evaluate for the future," said Mr Rahmat.

It was not clear whether the tsunami, which officials say hammered Palu and the surrounding area at extremely high speeds measuring in the hundreds of kilometres per hour, occurred before or after the warning was lifted.

"Based on the videos circulating on social media, we estimate the tsunami happened before the warning officially ended," Mr Rahmat said.

The scenic town of Palu sits at the mouth of a narrow bay in north-eastern Sulawesi and is home to around 380,000 people. It was hit by a tsunami in 1927 and 1968, according to Indonesia's national disaster management agency BNPB.

Dr Sutopo Purwo Nugroho, the spokesman for the agency, told reporters that his team had been "preparing to send public warnings that were easy to understand" when the tsunami warning was "suddenly ended".

The Communications Ministry said repeated warnings were sent out to residents via text message, but Dr Sutopo said the quake had brought down the area's power and communications lines and there were no sirens along the coast.