Mourners attend the funeral prayers for nine members of Alemdar family killed in a collapsed apartment building, in Istanbul, Saturday, Feb. 9, 2019.
Earlier, health minister Fahrettin Koca increased the death toll to 17.
Murat Kurum, Turkey's minister for environment and urban planning, said the collapsed building had permits for only six floors.
He said the government would take "steps in a determined way" after investigators complete their work. He said rescuers had reached another person under the rubble, who was thought to be dead. It was not immediately clear what caused the building.More news: French 'yellow vest' protester loses fingers in violent unrest
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"In this area, we have faced a very serious problem with illegal businesses like this done to make more money", Erdogan told reporters on his first visit to the site.
A majority of buildings in Istanbul are "either unlicensed, illegal or were constructed without any engineering services", they added.
The collapse fuelled criticism of a government amnesty granted past year to people accused of building illegally - a measure announced before municipal elections this March. Seven of them are in a serious condition.
"We estimate that there were 35 people trapped under the rubble and we have now accounted for 35", he said while stressing that search operations would continue as before.
Fourteen apartments, housing at least 43 occupants were registered at the site, the city's governor said this week.