Rescue crews used excavators to search for survivors trapped in toppled apartment buildings after a powerful pre-dawn earthquake in Albania killed at least 20 people and injured more than 600.

The 6.4 magnitude quake was felt across the southern Balkans early on Tuesday and was followed by multiple aftershocks.

In nearby Bosnia, another temblor with a preliminary magnitude of 5.4 struck south-east of the capital and rattled Sarajevo.

There were no immediate reports of casualties and only minor damage in that earthquake.

The quake in Albania knocked down apartment buildings and hotels while people slept, and rescue crews worked into the evening to free people believed trapped.

There was no indication as to how many people might still be buried in the rubble, as neighbouring countries and European Union nations sent search-and-rescue crews to help.

Local television stations showed footage in the early hours after the quake of a young boy being rescued from a collapsed building in the coastal town of Durres, 20 miles west of the capital Tirana.

An excavator moved a broken slab of concrete and the boy cried and shouted in pain as local men pulled mangled reinforcement bars out of the way trying to try to free his leg from the rubble.

Hours later, live TV footage showed people cheering as another child was found alive in a collapsed building in Durres where a body had been located earlier.

Albania Earthquake
Rescuers search at a damaged building in Thumane (Visar Kryeziu/AP)

In total, 43 people had been rescued from the rubble of buildings by Tuesday evening.

The Health Ministry reported about 600 people had been injured, including nine taken to hospital with life-threatening injuries.

“It is a dramatic moment where we should preserve calm, stay alongside each other to cope with this shock,” prime minister Edi Rama said, thanking countries that offered support.

The government declared Wednesday a day of mourning for the victims, saying flags would be flown at half-mast.

The US Geological Survey said the magnitude-6.4 quake, which struck just before 4am local time, had an epicentre 19 miles north-west of the capital, Tirana, at a depth of 12 miles.

Scores of aftershocks included three with preliminary magnitudes of between 5.1 and 5.4.

Albania Earthquake
Hundreds of people were injured in the quake (AP)

The worst-hit areas were Durres, where 11 of the dead were found in collapsed buildings, and the northern town of Thumane, where another seven bodies were pulled from the rubble, the Defence Ministry said.

In total at least three hotels, a residential villa and an apartment building collapsed in Durres, and one apartment building in Thumane.

One person died after jumping from his home to escape in Kurbin, 30 miles north of the capital, while another person was killed on a road that collapsed in the northern town of Lezha.

“Search and rescue work continues at all sites where buildings have collapsed,” defence minister Olta Xhacka said in a televised statement.

“But these are extremely difficult operations, where you have to work slowly because there is a high risk of further collapse, endangering not only residents, but also those trapped, and the rescuers themselves.”

Albania Earthquake
Rescuers search at a damaged building after the magnitude 6.4 earthquake (Hektor Pustina/AP)

Seismologist Rrapo Ormeni, of Albania’s Institute of Geosciences, Energy, Water and Environment, said a 6.4 quake was considered a strong one.

“Damage at the epicentre will be considerable because of its high energy, the magnitude it has,” Mr Ormeni said.

“Such quakes are felt in a wider area due to (their) major depth and magnitude. It has been felt all around the territory of our country but also abroad, up to Bulgaria, Bosnia, Italy and other (countries).”

The quake was also felt in neighbouring Kosovo, Montenegro, North Macedonia, Greece, and parts of southern Serbia.

All government agencies were on alert and “intensively working to save lives at the fatal spots in Durres and Thumane,” Mr Rama said.

About 400 soldiers were setting up tents in Durres and in Fushe Kruje near Thumane in the north to house survivors left homeless by the quake.

Albania Earthquake
Greece and Kosovo promised to help with the rescue (AP)

By Tuesday evening, rescue teams from neighbouring Kosovo, Montenegro, Italy, Greece and Romania had arrived.

Serbia, North Macedonia, Croatia, Hungary, Germany, France, Estonia, Turkey and the Czech Republic also offered help, while the EU delegation to Albania said additional EU assets were on standby should they be needed.

“My thoughts are with the victims and all the people affected by the disaster,” EU commissioner for humanitarian aid and crisis management Christos Stylianides said.

At least three apartment buildings and the power distribution station were damaged in Thumane, knocking out power in the morning. The electricity supply was restored later in the day.

An earthquake in September in roughly the same area damaged hundreds of homes.