AFP

A magnitude-6.1 earthquake struck northwest Turkey during Wednesday's early hours, injuring at least 22 people.

The shallow tremor struck about 170 kilometres (105 miles) east of Istanbul, the country's largest city, where it was strongly felt.

National authorities said the quake was at a magnitude of 5.9 -- lower than the 6.1 given by the US Geological Survey -- and its epicentre was in Duzce province's Golyaka district, though it also shook other nearby cities.

"We were woken up with a big noise and tremor," Fatma Colak, a resident of Duzce, told AFP.

"We got out of our homes in panic and now we are waiting outside."

Health Minister Fahrettin Koca tweeted that 22 people were injured -- including one who was seriously hurt after jumping from a building out of panic.

Initial images showed people covered in blankets outside their homes during the early morning. Some were seen placing blankets on the floor outside, and lighting fires for warmth.

Authorities said schools would be closed on Wednesday in Duzce and Sakarya provinces.

Interior Minister Suleyman Soylu said in televised comments that, apart from a few ruined barns, there were no reports of heavy damage or building collapses.

National disaster agency the AFAD said there were controlled blackouts in the Duzce region, urging residents not to panic.

Turkey is in one of the world's most active earthquake zones.

A magnitude-6.8 quake hit Elazig in January 2020, killing more than 40 people.

In November that year, a magnitude-7.0 quake hit the Aegean Sea, killing 114 people and wounding more than 1,000.

Turkey's worst quake in decades came in 1999, when a pair of strong earthquakes struck its northwest, killing around 18,000 people.