Morocco's deadliest earthquake in decades has killed over 1,000 people, authorities said Saturday, causing widespread damage and sending terrified residents and tourists scrambling to safety in the middle of the night.

The magnitude-6.8 quake struck a mountainous area 72 kilometers (45 miles) southwest of tourist hotspot Marrakesh at 11:11 p.m. (2211 GMT) Friday, the U.S. Geological Survey reported.

Strong tremors were also felt in the coastal cities of Rabat, Casablanca and Essaouira.

It is the strongest-ever quake to hit the North African kingdom, and one expert described it as the region's "biggest in more than 120 years".

"Where destructive earthquakes are rare, buildings are simply not constructed robustly enough ... so many collapse, resulting in high casualties," said Bill McGuire, professor emeritus at Britain's University College London.

Updated Interior Ministry figures on Saturday showed the quake killed at least 1,037 people, the vast majority in Al-Haouz, the epicenter, and Taroudant provinces.

Another 1,204 people were injured, including 721 in critical condition, the ministry said.

The ministry also recorded deaths in Ouarzazate, Chichaoua, Azilal and Youssoufia provinces, as well as in Marrakesh, Agadir and the Casablanca area.

Significant damage likely

The USGS PAGER system, which provides preliminary assessments on the impact of earthquakes, issued a "red alert" for economic losses, saying extensive damage is probable.

World leaders from China, the U.S. and other countries and international organizations expressed sympathies to the bereaved families and the injured and hoped the Moroccan government and people will be able to overcome the impact of the disaster and rebuild their homeland at an early date. 

The earthquake was also felt in neighboring Algeria, where the Algerian Civil Defense, the country's public emergency response service, said it had not caused any damage or casualties.

In 2004, at least 628 people were killed and 926 injured when a quake hit Al Hoceima in northeastern Morocco, and in 1960, a magnitude-6.7 quake in Agadir killed more than 12,000.

In 1980, the magnitude-7.3 El Asnam earthquake in Algeria killed 2,500 people and left at least 300,000 homeless.

(With input from AFP)