Istanbul deputy mayor shot in the head in city hall

The mayor of the city's Sisli district is in a critical condition in hospital

Anti-coup protesters wave a Turkish flag on top of the monument in Taksim square, Istanbul, (AP)

An unknown assailant has shot the deputy mayor of Istanbul's Sisli district in the head.

According to Turkish broadcaster NTV, the victim was in a critical condition.

It was not immediately clear whether the incident was linked to Friday's abortive military coup in which more than 200 people were killed.

Turkey remains in a state of high tension, though the government says it has the situation fully under control.

Turkish President Recep Tayyip Erodgan has said he will rid the country's institutions of the "virus" of those who oppose him.

More than 7,000 people - including over 100 generals - have been arrested following the coup.

It comes as Turkish Prime Minister Binali Yildirim has suspended the annual leave of more than three million civil servants nationwide until further notice, according to a government order published on Monday.

The order, published in Turkey's Official Gazette, comes amid a wide-ranging government purge of the civil service, judiciary, police and armed forces following an abortive coup attempt by a faction of the army on Friday evening.

Civil servants already on leave will return to their posts as soon as possible, the order said.