The deadly explosion in a Rotterdam apartment block was probably caused by a blast in a drugs laboratory, police confirmed at the weekend.

The debris left after the blast included items that could have been used in the production of hard drugs and the 34-year-old man who rented the lock-up has now been arrested, police said. His role in the explosion is now being investigated.

The man who was arrested was the uncle of one of the three men killed in the explosion. According to local broadcaster Rijnmond, he is also one of the two men who broke through the fence that had been placed around the scene and spotted body parts.

The police have not ruled out other arrests.

Earlier in the week, journalists had seen jerry cans containing chemicals being removed from the rubble and the rescue work was halted for a time because a leaking vat began to smoke, Rijnmond reported.

A police spokesman also told Rijnmond that scales and a sieve were also recovered at the scene. “Things that when put together would indicate drugs,” the spokesman said.

The explosion took place in the lock-up under a low-rise housing block and the resulting fire left seven homes to be declared uninhabitable. Dozens of others were seriously damaged.