Kurdish militants detonated a roadside bomb in the southeastern province of Sirnak overnight, killing three police officers and wounding four others in an armoured vehicle, security sources said on Monday.

The mainly Kurdish southeast has been rocked by daily violence since a 2013 ceasefire between the state and Kurdistan Workers Party (PKK) militants collapsed last July, reigniting a three-decades-old conflict that has killed 40,000 people.

Sources said the blast occurred around 11:30 p.m. (2130 GMT) in the Idil district of Sirnak, near the border with Syria, and simultaneously PKK fighters attacked a security force base in the area with rifles. There were no casualties in that attack.

The PKK, which says it is fighting for autonomy for Turkey's Kurds, took up arms against the state in 1984. It is designated a terrorist group by Turkey, the United States and European Union.

The towns of Cizre and Silopi, further east of Idil in Sirnak, have been under round-the-clock curfew since Dec. 14 as security forces battle Kurdish fighters there.

Turkey's army says it has killed 320 militants in Cizre, 135 in Silopi and 101 in the Sur district of Diyarbakir city since operations began last month. The pro-Kurdish HDP party says some 100 civilians have been killed in these areas.