ISTANBUL,— Kurdish militants killed five members of the Turkish security forces on Thursday in a series of clashes and bomb attacks in a town under a military lockdown in Turkish Kurdistan, the southeast of the country, the Dogan news agency reported. The Turkish security forces were carrying out an operation in the town of Nusaybin in Mardin province where the government has been waging a blistering offensive against the Kurdistan Workers Party (PKK). A senior police officer was hit by gunfire and later died, and four other members of the security forces, including a major in the gendarmerie and another senior police officer, died in two separate bomb attacks. Nusaybin has been under curfew since mid-March for a military operation to push the PKK out of the town, where the authorities say the group has dug trenches and put up barricades. Hundreds of security forces have been killed in the Kurdish region, while government says thousands of PKK militants have died. Opposition political parties say between 500 and 1,000 civilians, mostly Kurds, have also perished in the fighting, since the Turkish offensive against the PKK centred in towns and cities in Turkish Kurdistan. Ankara launched the offensive against the PKK after the collapse in 2015 of a two-year long ceasefire with the group that has been a thorn in its side for three decades. The renewed conflict has also struck the heart of the country, with two attacks that killed dozens in the capital Ankara claimed by Kurdish rebels, at a time when citizens are already on high alert over bombings by the Islamic State group. President Recep Tayyip Erdogan on Tuesday proposed stripping Turkish citizenship from supporters of Kurdish rebels. “These people don’t deserve to be our citizens. We are not obliged to carry anyone engaged in the betrayal of their state and their people,” he said. A day after his comments his Justice Minister Bekir Bozdag said: “Of course we will begin work on this”. he PKK took up arms in 1984 against the Turkish state, which still denies the constitutional existence of Kurds, to push for greater autonomy for the Kurdish minority who make up around 22.5 million of the country’s 78-million population. A large Turkey’s Kurdish community openly sympathise with PKK rebels. The European Union has urged last week Turkey to restart the peace process with the Kurd.