Medics treated a constant flow of casualties after Morocco's strongest-ever earthquake killed more than 2,800 people, but hopes were fading Tuesday of finding more survivors under the rubble.

Rescuers supported by foreign teams faced a race against time to find those still alive after villages in the Atlas mountains were devastated by the 6.8-magnitude disaster that struck over the weekend.

It was the deadliest quake to hit the North African country since a 1960 earthquake destroyed Agadir, killing thousands.

The epicentre of Friday's late-night tremor was in Al-Haouz province southwest of the tourist hub of Marrakesh. Most of the victims died in Al-Haouz, authorities reported.

Overall, at least 2,862 people died and more than 2,500 were injured in the tragedy, according to an official toll late Monday.

Moroccan rescuers backed by teams from Spain, Britain, Qatar and the United Arab Emirates are now up against the clock.

"The big difficulty is in zones remote and difficult to access, like here, but the injured are choppered out," Annika Coll, who heads the Spanish team, told AFP in the disaster-stricken community of Talat Nyacoub.

About 70 kilometres (40 miles) north, another Spanish team from the Military Emergencies Unit (UME) had set up camp since late Sunday on the edge of Amizmiz village.

Albert Vasquez, the Spanish unit's communications officer, warned Monday that "it's very difficult to find people alive after three days" but "hope is still there".

Rabat on Sunday announced it had accepted offers to send search and rescue teams from Britain, Qatar and the UAE, as well as Spain.

Many other nations have offered to help.

- Spanish reinforcements -

Madrid said late Monday it was reinforcing its presence on the ground in Morocco with another five canine rescue teams comprising "31 specialists, 15 search and rescue dogs and 11 vehicles" arriving on Tuesday.

The earthquake wiped out entire villages in the Atlas foothills, where civilian rescuers and members of Morocco's armed forces have been searching for survivors and the bodies of victims.

Citizens reported to hospitals in Marrakesh and elsewhere to donate blood, while other volunteers organised food and essential supplies to help quake victims, after complaints that authorities were slow to respond.

The education ministry announced that classes have been "suspended" in the worst-hit villages of Al-Haouz province.

One volunteer helper, Yacine Benhania, complained of a "shortage of medicines, particularly for diabetes and hypertension".

At a makeshift hospital under canvas in Amizmiz, where the local hospital is considered unsafe because of the possibility of aftershocks, emptied beds were quickly refilled by constant arrivals.

But doctors have flocked to the area from across the country to help treat the wave of quake casualties.

"We can't treat everything here", said ophthalmologist Doha Hamidallah from Casablanca.

"We handle primary treatment such as sutures and fractures. But more serious cases are sent to Marrakesh University Hospital."

Prime Minister Aziz Akhannouch said he had chaired a meeting on Monday on housing and reconstruction in the affected areas.

"Citizens who have lost their homes will receive compensation," he announced, saying specific details were being decided.