A damaged car is seen under the ruins, after an earthquake hit the Varankesh village in Eastern Azerbaijan province, northwest of Tehran. Photo: Tasnim News Agency/WANA (West Asia News Agency) via REUTERS.

Tehran - At least five people were killed and more than 300 injured as a 5.9-magnitude earthquake hit north-western Iran in the early hours of Friday morning, Iranian media reported.

Reports said at least 400 houses had been damaged.

The quake struck at 2:17 am (22:47 GMT) some 50 kilometres north-east of Hastrud, a city in Iran's north-west towards the borders with Armenia and Azerbaijan, according to the US Geological Survey (USGS).

"Rescue teams and helicopters have been dispatched to the quake-hit areas and hospitals are on full alert to help injured people," Iran's emergency medical services chief Pirhossein Kolivand was quoted as saying by Press TV's English website.

Army units have also been put on standby.

The European-Mediterranean Seismological Centre (EMSC) estimated that 20 million people in the area felt the quake.

President Hassan Rowhani has called the local governor and ordered all resources available to deal with the emergency, Press TV said.

Iranian officials said 80 villages were affected. The majority of the damage hit villages in the area around the city of Tark.

Around 50 aftershocks have also been felt in the region, up to a magnitude of 4.8, and led to people sleeping outside in the cold due to fears of buildings collapsing.

Photographs from the scene showed masonry had fallen on top of cars and buildings had been severely damaged.

Moderate to large earthquakes occur regularly in eastern Turkey and north-west Iran, the US survey added, with other areas of Iran also vulnerable.

A 6.6-magnitude quake in the south-eastern Iranian city of Bam in 2003 killed around 26,000 people.