DIYARBAKIR, Turkey (Reuters) - Turkey’s pro-Kurdish party leader called for “honourable resistance” against security operations in southeast Turkey on Friday as state media reported 55 Kurdish militants had been killed in three days of urban fighting there.

Riot police use a water cannon to disperse demonstrators during a protest against the curfew in Sur district, in the southeastern city of Diyarbakir, Turkey, December 18, 2015. REUTERS/Sertac Kayar

In Cizre, near the Syrian border, gunfire rattled and smoke rose from buildings, while a helicopter flew over the town, Reuters TV footage showed. A soldier and two other people were killed in the latest clash there, security sources said.

The figures indicated a doubling of the death toll in the last 24 hours after President Tayyip Erdogan promised on Thursday the Kurdistan Workers Party (PKK) fighters would be “annihilated”.

A two-year ceasefire between the PKK and Ankara fell apart in July, shattering peace talks and reviving a conflict that has afflicted the mainly Kurdish southeast for three decades, killing more than 40,000 people.

The latest unrest also hit the mainly Kurdish region’s largest city, Diyarbakir, where police fired water cannon and tear gas at thousands of people protesting over security operations, which have also targeted its historic Sur district.

Witnesses said people scattered into side streets as the intervention began, coinciding with a call from pro-Kurdish Peoples’ Democratic Party (HDP) co-leader Selahattin Demirtas for people to resist the operations.

“We call on our people to expand the struggle and to embrace this honourable resistance,” he told a news conference.

“If they think they can make us take a step back by showing a tank gun, they are wrong. We fear nobody but God. We call on all civil society groups to embrace resistance in the lands of Kurdistan,” he said.

Anadolu news agency said 49 PKK fighters were killed in Cizre and six in Silopi, while 19 security force personnel were wounded and three militants were taken into custody alive.

Both towns were placed under curfew on Monday before an operation which Turkish media say involves 10,000 police and troops backed by tanks.

Traditionally active in the countryside, the PKK has shifted focus in recent years to towns in the southeast. Ankara has responded with intensified operations against the PKK, designated as terrorist by Turkey, the United States and European Union.

In Diyarbakir, Demirtas reaffirmed his party’s belief that autonomy and self-government, something sought by many Kurds, were the right model for Turkey and “important decisions” on building self-government would be taken at a Diyarbakir congress this month. “We want a return to a healthy negotiating process where autonomy and self-government is discussed,” he said.

Peace talks launched in late 2012 between the PKK’s jailed leader Abdullah Ocalan and the state ground to a halt early this year ahead of elections, where the HDP exceeded the 10 percent threshold of votes needed to enter parliament.