A magnitude-6.9 earthquake has struck 284km south-west of the Fiji capital Suva, the US Geological Survey (USGS) says.
The USGS said the quake was at a depth of 15.2km and an aftershock measuring magnitude-5.7 had also been recorded.
The Pacific Tsunami Warning Centre has withdrawn a tsunami warning for parts of the Pacific located 300km from the epicentre.
Radio New Zealand reported people had been evacuating the Fijian tourist hub of Nadi since the earthquake struck.
There have been no reports of damage or injury from Fiji.
“We felt it [the quake] ever so slightly in Suva,” Sune Gudnizt, head of the United Nations’ Office for the Coordination of Humanitarian Affairs said.
Red Cross Australia aid worker Susan Slattery said “pretty much everybody in Suva” evacuated buildings for higher land after the quake, fearing a tsunami.
“Certainly the whole city was on the move,” she said.
There are some level of earthquakes in and around Fiji fairly constantly or fairly often but this level of earthquake is unusual and certainly this close to the main islands is unusual and having the resultant tsunami warning is not common.”
Kelvin Anthony said he was working in an office building in central Suva when a “slight tremor” was felt.
“Before the advisory came, one of our managers, who has sort of had, I guess, previously been in situations like this, quickly advised everyone that that’s an earthquake and that we’ve got to move,” he told the ABC.
“We also had power cuts, so it went on off, on off, about two or three times.”
‘Unusual’ that tremor occurred away from plate boundary
Spiro Spiliopoulos, senior seismologist at Geoscience Australia, said the tremors happened close to a tectonic plate boundary between the Australian plate and the Pacific plate, where a large number of earthquakes are recorded.
“This is unusual in that it occurred a little bit away from the plate boundary,” he told the ABC.
“They have the potential to generate tsunamis.”
Geoscience Australia said main tremor would have been felt in the Pacific islands of Vanuatu, New Caledonia, Tonga and parts of American Samoa.
A magnitude-6.3 quake hit 582km south of Suva on Monday at a depth of 555km.
Small quake hits south of Sydney
Meanwhile, a town in NSW has been rocked by a small earthquake in the early hours of Wednesday morning.
The magnitude 3.9 earthquake hit Appin about 1.15am and had a wide range, which meant it could be felt by Wollongong residents, who live about 35km away, Geoscience Australia said.
More than 100 people in the area called Geoscience to report they had felt the earthquake, which is strong enough to give someone a bit of a shake while they are in bed, a spokesman said.
Appin has a history of earthquakes, with an average of one tremor every one to two years over the past decade.
– with ABC and AAP