TURKEY’S president has visited the scene of an apartment building collapse in Istanbul as the death toll increased to 17.

The cause of last week’s tragedy is still under investigation but officials have said the top three floors of the eight-storey building in the Kartal district were built illegally.

Speaking at the scene, President Recep Tayyip Erdogan said there are “many lessons to learn”.

He added: “In this area, we have faced a very serious problem with illegal businesses like this done to make more money.”

He said the government will take “steps in a determined way” after investigators complete their work.

Earlier, health minister Fahrettin Koca increased the death toll to 17.

Erdogan also visited a hospital where more than a dozen people injured in the collapse are being treated. Seven of them are in a serious condition.

Emergency teams, aided by sniffer dogs, are continuing to work around the clock to reach possible survivors.