Cell phone footage of restoration workers drilling down the stone wall of Istanbul's 14th-century Galata Tower created a political firestorm Wednesday and forced the culture ministry into a hasty retreat.

The iconic 67-metre (220-foot) structure overlooking the Golden Horn is a massive draw for tourists and an enduring symbol of Istanbul.

It was the ancient city's tallest structure when completed by the Genoese in 1348. But its future looked in sudden doubt when a press officer of the Istanbul city government tweeted a clip of two restoration workers taking apart a corner section of the tower's inner wall with jackhammers.

A pile of large stones lay at their feet as they worked. "It was really shocking to see this kind of vandalism being performed in the most important cultural site of Istanbul," the city's cultural heritage department director Mahir Polat said. "This conduct is insane."

The 20-second clip became a social media sensation and made the tower a trending topic on Turkish Twitter. Galata was already a source of tension between the city -- whose mayor Ekrem Imamoglu is a prominent opponent of President Recep Tayyip Erdogan -- and the Turkish culture ministry.

The ministry tried to take over control of the tower immediately after Imamoglu's hotly disputed election last year. The transfer was held up in court but formally completed in April.

Culture Minister Nuri Ersoy explained in his own tweet a few hours later that the workers were removing "parts that were added (to the wall) later on and that were damaging the Galata Tower".

But he said that the workers responsible were reprimanded nonetheless. "Regarding the techniques used in the restoration, the necessary sanctions have taken against the relevant contractor," the minister tweeted.

Ersoy's deputy explained that the workers were transforming a part of the tower that used to house a restaurant into a museum. But the city's cultural heritage department director was unconvinced. "It is inadmissable to see Istanbul destroy its treasures," he said.

The tower is scheduled to reopen to tourists once the restoration work is completed on September 15.