At least 16 people died when a half-built apartment block collapsed in the Moroccan city of Khenitra and local officials said more could be trapped under the mass of rubble and twisted steel.

Rescuers dragged out another body on Thursday afternoon, almost 24 hours after the collapse, as diggers heaved aside piles of concrete slabs. Hundreds of residents looked on from behind metal barriers. Twenty-six people were injured.

Many of the victims were builders having lunch in the building's basement.

"I felt something like an earthquake and rushed out to find the building totally flattened," said local resident Mohammed L'Khnati, 30. "I ran over and some of us dragged two people free but I could hear others trapped inside, crying for help."

The building was part of a low-cost housing and commercial project managed by real estate firm El Manal on the outskirts of the fast-growing city which lies 40 km (25 miles) north of Rabat, said Khenitra provincial councillor Miloud Lakhdar.

He cited experts as saying the building could have collapsed because concrete joists used to hold the upper floors may not have been strong enough to carry the load. The full cause was yet to be established by the authorities.

"Normally there are inspections every time big beams are put in place, so I wonder whose mistake this was," said Lakhdar. "This company has a good record, with similar constructions in Rabat and Casablanca."

He said around 50 workers had been on site at the time, most from rural provinces who left their homes in search of work.

Interior Minister Chakib Benmoussa, who visited the scene with other senior officials, vowed to identify and punish those who might be responsible.

Like other Moroccan cities, Khenitra is expanding fast as people from the countryside migrate to the towns in search of work and the government moves to replace slums with affordable apartments.

"This is a wake-up call. We're in the middle of a construction boom and there are some people who rush after quick profits," said Lakhdar.