The number of people confirmed to have died in Friday night’s earthquake has risen to 2,497, according to Morocco’s state news agency.
It is an increase of 375 from the 2,112 people confirmed dead as of Sunday.
Experts have warned the number could keep rising as rescuers reach remote rural areas and search operations continue.
Rescuers are in a race against time to reach those trapped under collapsed buildings – with pockets of air key to keeping survivors alive.
But experts have warned that the traditional mud brick, stone and rough wood materials used to build many of the structures in the High Atlas mountains “turned to rubble” as they collapsed.
Antonio Nogales, coordinator of operations for Firemen United Without Borders, a Spanish rescue team on the ground, told Spain’s TVE: “This kind of collapse causes greater air tightness due to the types of material, like mud brick.
“Steel and concrete facilitate the possibility of survivors, but these [mud and brick] materials mean that in the first moments the chances of getting people out alive are reduced.”
An unnamed military source within the rescue operation added: “It’s difficult to pull people out alive because most of the walls and ceilings turned to earthen rubble when they fell, burying whoever was inside without leaving air spaces.”
The worker, who spoke to the news agency Reuters, asked not to be named because of army rules against speaking to media.
Meanwhile, Friday night’s earthquake is the most deadly to hit Morocco in more than 60 years.
The last was in 1960 and struck Agadir – a city on Morocco’s southern Atlantic coast.
Despite its moderate 5.8 magnitude – significantly smaller than Friday’s 6.8 magnitude earthquake – the 1960 tremor was at a relatively shallow depth.
It resulted in violent surface tremors, destroying large parts of the city and killing between 12,000 and 15,000 people – a third of the city’s population at the time.
A further 12,000 were injured, with at least 35,000 people left homeless.
Morocco also experienced the impacts of the powerful 7.8 magnitude earthquake in Portugal in 1969.
A total of 13 people died – 11 in Morocco and two in Portugal.
Around 630 people also died and a further 926 were injured during the 6.3 magnitude earthquake in Al Hoceima, on Morocco’s north coast, in 2004.
Perhaps the most deadly, however, struck Morocco in 1755 – an earthquake which devastated the cities of Fez and Meknes.
More than 15,000 people are thought to have died in the earthquake.