At least two protesters have been killed in clashes with Turkish police over a government-imposed curfew in the southwestern city of Diyarbakir, security sources say.

The clashes erupted for a second day on Monday, when thousands of people tried to march to the Sur district to condemn a curfew declared there nearly two weeks ago.

Police used water cannon and fired tear gas to disperse the demonstrators who had erected barricades and lit a fire on a road in the area.

Two demonstrators, aged 21 and 25, were both shot dead in the violent clashes.

Riot police use water cannons to disperse demonstrators in Sur district, the southeastern city of Diyarbakir, Turkey, December 14, 2015. (Reuters photo)

The restrictions on the free movement of people imposed by the Turkish government are purportedly aimed at facilitating counter-terrorism operations against the Kurdistan Workers’ Party (PKK) militant group.

The demonstrators in the troubled city were joined by several lawmakers from the pro-Kurdish and left-wing People’s Democratic Party (HDP) on Sunday and marched toward the armored police vehicles deployed to the area and set fire to tires to block the streets. They also engaged in clashes with police.

Sur sees frequent clashes between security forces and Kurdish youths.

Turkey has been engaged in a large-scale military campaign against the PKK in its southern border region over the past few months. The Turkish military has also been conducting offensives against the positions of the PKK in northern Iraq.

The operations began in the wake of a deadly bombing on July 20 in the southern Turkish town of Suruc, an ethnically Kurdish town located close to border with Syria. Over 30 people died in the Suruc attack, which the Turkish government blamed on Takfiri Daesh terrorists.

After the bombing in Suruc, the PKK militants, who accuse the government in Ankara of supporting Daesh, engaged in a series of supposed reprisal attacks against Turkish police and security forces, in turn prompting the Turkish military campaign.