Tsunami waves observed in American Samoa after 7.3 magnitude earthquake jolts island nation Tonga

"An urgent tsunami advisory is now in force for all of Tonga due to a strong earthquake being felt in the Kingdom tonight. Please move inland immediately until further advised," Tonga's meteorological service said.

The government of Tonga issued a tsunami warning on Friday after an earthquake of magnitude 7.3 struck in the sea around 207 km (128 miles) from the capital, and warned residents to move inland to higher ground.

The earthquake was at a depth of 24.8 km (15.4 miles) that struck in the sea at about 207 km (128.6 miles) east of south-east of Neiafu. (AP file)

The earthquake was at a depth of 24.8 km (15.4 miles) that struck in the sea at about 207 km (128.6 miles) east of south-east of Neiafu, according to the United States Geological Survey (USGS).

A tsunami advisory was also issued for American Samoa, according to the Pacific Tsunami Warning Center (PTWC). Hazardous tsunami waves from the earthquake are possible within 300 km of the epicentre along the coasts of Niue and Tonga, it said.

Tonga's meteorological service warned residents to move inland. The island nation is a country of about 100,000 people and spreads across 171 islands.

"An urgent tsunami advisory is now in force for all of Tonga due to a strong earthquake being felt in the Kingdom tonight. Please move inland immediately until further advised," it said on its Facebook page.

Officials initially gave the magnitude at 7.1, but later revised it up to 7.3.

In January, the Hunga Tonga-Hunga Ha'apai volcano eruption triggered a tsunami that destroyed villages and resorts and knocked out communications for the South Pacific nation of about 105,000 people. At least three people were killed.