ANKARA — Three Turkish police officers and six Islamic State militants were killed in a shootout during a counter-terrorism operation in Yalova province Monday, authorities said.

The gunfight in northwest Turkey, in which nine other officers were wounded, took place a week after more than 100 suspected IS members were detained for planning Christmas and New Year attacks.

The clash erupted around 3 am local time when police raided a house in Elmalik village, about 9 kilometers from Yalova city centre in the country's northwest, suspected of harbouring IS members. Suspects opened fire as officers approached, triggering an exchange of gunfire.

Six IS members were killed in the shootout, according to reports.

All wounded officers were taken to Yalova Training and Research Hospital and were not in life-threatening condition, according to the Yalova Governorate.

Special operations units from neighbouring Bursa province were dispatched to provide support, and the operation continued with security measures in place around the scene. Authorities suspended classes at five nearby schools and sealed off roads approaching the house.

It was not immediately clear whether any suspects were wounded or arrested. Turkey's broadcasting regulator imposed a temporary media ban on coverage of the incident, instructing outlets to only report official statements.

The operation comes as Turkish authorities intensified counter-terrorism efforts ahead of New Year celebrations following intelligence warnings of potential IS attacks.

On 25 December, Istanbul police detained 115 suspected IS members in raids across 124 locations following intelligence that the group was planning attacks during Christmas and New Year celebrations. Police issued arrest warrants for 137 suspects and seized pistols, ammunition and organisational documents. Operations to apprehend the remaining 22 suspects are continuing.

Turkey's National Intelligence Organisation captured Mehmet Gören, codenamed "Yahya", in the Afghanistan-Pakistan border region on 22 December and brought him to Turkey. Gören, described as a senior figure in IS' ofshoot ISIS Khorasan Province, was allegedly assigned to conduct suicide attacks in Turkey, Pakistan, Afghanistan and Europe, security sources said.

Gören had been operating alongside Özgür Altun, codenamed "Abu Yasir Al Turki", who was previously captured from the same region and arrested. Altun allegedly played an active role in transferring ISIS members from Turkey to the Afghanistan-Pakistan region.

On 23 December, Ankara prosecutors detained 10 suspects accused of financing ISIS. Investigations by the Terrorism Crimes Investigation Bureau, using Financial Crimes Investigation Board reports and social media analysis, revealed the organisation's Ankara structure, prosecutors said.

The suspects allegedly transferred cash to IS members and their families in Syrian conflict zones through bank accounts with descriptions such as "call for unity, atonement, aid for captive sisters", according to authorities.

Turkish intelligence and police also detained İbrahim Burtakuçin in Malatya over allegations he was preparing a New Year attack. Security sources said Burtakuçin was in contact with IS members abroad, and digital materials and banned publications were found at his residence.

Internal correspondence from Ankara Provincial Gendarmerie Command dated 19 December warned that IS was seeking to carry out attacks in crowded areas on New Year's Eve, according to Cumhuriyet newspaper.

The warning said the group may plan armed attacks, suicide bombings, car bombings, drone attacks or vehicle-ramming incidents, particularly targeting shopping malls and public markets.

On 10 October 2015, IS suicide bombers attacked a peace rally outside Ankara railway station, killing at least 102 people and injuring over 400 in the deadliest terror attack in Turkish history. Trials related to the attack remain ongoing.

On 1 January 2017, a gunman attacked Reina nightclub in Istanbul during New Year's celebrations, killing 39 people.

In addition, hundreds of civilians lost their lives in IS attacks on Atatürk Airport, Suruç and Diyarbakır between 2015 and 2017. — Agencies