At least 8,326 people have now been confirmed dead and nearly 40,000 injured following the devastating 7.8-magnitude quake that stuck Turkey and Syria earlier this week, with aid agencies saying that the figures could significantly rise as many people still remain trapped under the rubble.

Addressing a news conference on Wednesday, Turkish Vice President Fuat Oktay said the death toll in the country currently stood at 5,894, while the number of injured persons spiked to 34,810, reports Anadolu News Agency.

"The loss of every citizen deeply saddens us," Oktay told reporters, adding that authorities are continuing their rescue efforts to reach out to survivors.

As many as 5,775 buildings collapsed, he said, adding that more than 8,000 people have been rescued from the rubble of the buildings.

In its latest update, Turkey's Disaster and Emergency Management Presidency (AFAD) said that total of 60,218 emergency officials are working in the affected-areas, including 3,200 personnel from 65 countries.

In Syria, the death toll has increased to 2,470, Xinhua news agency quoted officials as saying.

Of the overall fatalities, 1,250 were reported in government-controlled areas and 1,220 in rebel-held regions of the war-torn nation.

The regions of Aleppo, Lattakia, Hama, Idlib and Tartus were the hardest-hit.

More than 60 countries have pledged support and sent humanitarian aid to the affected regions in the two nations, while there are about 20 international government search and rescue teams on the ground presently.

Freezing weather conditions are further endangering survivors and complicating rescue efforts, as more than 100 aftershocks have struck the region since the initial tremor on Monday.

In Turkey, rescue workers were scattered across the vast quake-hit zone, which covers 10 provinces which are home to around 13.5 million people.

But as the quakes have also seriously disrupted the zone's infrastructure, making highways and roads inaccessible, some cities were left mostly unattended.

In Gaziantep, Adiyaman and Malatya, three provinces hit by the quakes, survivors took shelter in community centres where they were given blankets and food, television channels reported.

Mosques in the region were also opened to provide shelter.

The World Health Organization has warned that the death toll in the two countries could end up surpassing 20,000.

The earthquake-stricken region in Turkey is also home to hundreds of thousands of Syrian refugees who have fled the civil war in their homeland.

The devastating 7.8 tremor struck Turkey's southern province of Kahramanmaras at 4.17 a.m. on Monday morning, which was followed by a 6.4-magnitude temblor a few minutes later in Gaziantep province.

The epicentre of the 7.8-magnitude quake was 23 km east of Nurdagi in Gaziantep, at a depth of 24.1 km, according to the US Geological Survey (USGS).

At around 1.30 p.m, a third 7.5-magnitude tremor hit Kahramanmaras, which officials said was "not an aftershock".

Turkey's southern province of Hatay and Syria's northern Aleppo city suffered the biggest casualties, while Lebanon, Israel and Cyprus also felt the tremor.

Turkish President Recep Tayyip Erdogan declared a three-month state of emergency on Tuesday in the 10 provinces.

Turkey is also is observing a seven-day period of national mourning.