Indonesia has issued a tsunami warning after an earthquake of magnitude 7.5 struck its region of East Nusa Tenggara, the meteorological department says.

The European-Mediterranean Seismological Centre estimated the magnitude at 7.7, placing it at a depth of five kilometres.

It struck 91 kilometres north of Maumere, on Flores Island, in Indonesia’s east at 11.20am local time on Tuesday (2.20pm AEDT).

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TV footage reportedly showed people running from buildings as they shook from the impact. But there were no immediate reports of casualties or damage.

“Everyone ran out into the street,” Agustinus Florianus, a resident of Maumere told Reuters.

Shortly after the quake, the US Geological Survey said “hazardous tsunami waves are possible for coasts located within 1000 kilometres of the earthquake epicentre”.

Tsunami warnings were issued for the areas of Maluku, East Nusa Tenggara, West Nusa Tenggara and Southeast and South Sulawesi.

A 5.6-magnitude aftershock hit Larantuka after the first quake, the agency said.

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Alfons Hada Betan, head of East Flores Disaster Mitigation agency in Larantuka said there were no immediate reports of damage and the quake was felt for several minutes as people fled from their homes.

People said on social media the earthquake was also felt strongly in Makassar, South Sulawesi.

A tsunami warning was immediately issued for nearby coastlines but quickly downgraded to an advisory. BMKG said people in the area should move away from the beach, but evacuations were not required.

The USGS estimated that up to 21 million people might have felt the tremor.

Indonesia straddles the “Pacific Ring of Fire”, an area of high seismic activity that rests atop multiple tectonic plates.

At least 48 people were killed and hundreds injured when the Mount Semeru volcano erupted on Java island on December 4.

-with AAP