At least 17 people have died and 12 others have been injured in an explosion at an iron and steel factory near the port city of Izmir in western Turkey.

All those killed and injured were workers at the Habas Demir Celik plant in Aliaga, one of the country's leading steel producers, authorities said. Footage from the scene showed a large fire inside the facility and a towering column of smoke rising into the air.

The local governor said the blast happened around midday after a crane carrying a replacement boiler collapsed, causing materials to fall into a furnace below.

Workplace accidents remain a chronic problem in Turkey, the Turkish Health and Safety Labor Watch, an independent civil society organisation, said.

President Recep Tayyip Erdoğan originally said the death toll was 16, but later Health Minister Kemal Memişoğlu announced that one of those who had been critically injured had later died of their injuries, taking the toll to 17.

Eyewitnesses at the scene of the incident said the explosion shook the ground, with one person initially believing an earthquake had struck.

In a statement, the company that runs the factory said the accident occurred during scheduled maintenance work on one of the plant's electric arc furnaces.

Izmir Governor Süleyman Elban told media that some people were believed to still be under the rubble.

Speaking after a cabinet meeting on Monday, Erdoğan confirmed the deaths and said investigations were under way, while search and rescue operations continued.

At least five people have been arrested, according BBC News's Turkish service, citing local media reports.

The Habas plant is in the Izmir district of Aliaga which is a major port and one of Turkey's main shipbreaking hubs.