Angry relatives of the dozens still missing demanded punishment for the contractors they said were responsible for the building's collapse in the central Turkish city of Konya.

They should be put "in prison forever," said Ahmet Kalem, who lived with his family on the third floor. His wife and two sons were among the missing.

Rescuers on Wednesday found no survivors and admitted chances were slim of saving the 40 to 100 people still feared trapped.

Thirty-one people were pulled from the wreckage in the hours after the building collapsed on Monday.

Police detained two of the building's contractors and a team of prosecutors and engineers were probing the possibility of negligence in the building's construction.

Poor construction

Police Chief Salih Tuzeu said authorities suspected sub-standard building materials may have led to the sudden collapse.

Some 140 people lived in the building's 37 apartments, but it was unclear how many people were inside at the time of the disaster.

Many families had been celebrating the Muslim holiday of Eid-al-Adha with friends and relatives when the building collapsed.

The last survivor was pulled out on Tuesday evening.