A tsunami warning has been lifted in parts of the South Pacific following a powerful earthquake off the Solomon Islands.

The 7.8 magnitude quake struck about 70km (43 miles) off Kirakira, according to the US Geological Survey.

It said it had occurred at about 17:40 GMT (04:40 Friday local time), followed by many aftershocks.

Phones and electricity went down in some areas. There were no reports of casualties.

In Malaita, an island close to the epicentre, there were reports of collapsed buildings but the extent of the damage was still unknown, Solomon Islands National Disaster Management Office director, Loti Yates, told Reuters news agency.

A helicopter has been sent to assess the situation in Malaita, which is home to about a quarter of the Solomon Islands population of 600,000, he added.

People in many regions moved to higher ground, and users on social media said some places were evacuated.

Minor sea level fluctuations may continue in the next few hours, the Pacific Tsunami Warning Center said. Social media reports suggested a wave of around 20cm in the capital, Honiara.

The Solomon Islands are located in the so-called "Ring of Fire" in the Pacific, a zone of major seismic activity which has one of the world's most active fault lines.