A strong earthquake of 6.8 magnitude struck off Fiji on Sunday following a 6.3 magnitude quake that hit off Tonga, US seismologists said.
The US Geological Survey (USGS) said on its website that the offshore quake centered around 100km (62 miles) northeast of the Fijian island of Ndoi at a depth of 594 km.
Authorities said the earthquake occurred at 9.28 am local time (2128 GMT Saturday), 20 minutes after the 6.3 magnitude quake hit 124km northwest of Tonga.
The Hawaii-based Pacific Tsunami Warning Center said none of the quakes posed a tsunami threat and there were no reports of any damage or injury.
However, in its preliminary impact assessment, the USGS said there was a low possibility of casualties and damage.
The Fiji Islands are located in seismically active zones and hence they are prone to experience earthquakes.