A magnitude-7.1 earthquake struck in the sea off Tonga late Friday, according to the US Geological Survey, sparking a tsunami warning.

According to the USGS, the earthquake hit 10 km (six miles) deep, about 200 km southeast of Neiafu, a town in the northeast of the Pacific archipelago nation.

"Hazardous tsunami waves are possible for coasts located within 300 km of the earthquake epicenter," said the Pacific Tsunami Warning Center.

Seismic activity is fairly common around Tonga, a country with about 100,000 people spread across 171 islands.

In January this year, it was rocked by the eruption of the Hunga-Tonga-Hunga-Ha'apai volcano, one of the most powerful such events in modern times, according to researchers from the University of Bath.