TUNCELI (Reuters) - Three guerrillas of the Kurdistan Workers Party (PKK) were killed in two clashes with security forces in south-eastern Turkey at the weekend, army sources said Sunday. Two PKK fighters were killed in a clash with troops on Sunday near the town of Uludere in Sirnak province which borders Iraq, the sources said. A gun battle broke out after soldiers pursued a group of rebels who had detonated explosives on a road as a military vehicle passed, they said. No one was hurt in the blast. Late Saturday, one PKK guerrilla was killed when his group attacked a police checkpoint near the town of Beytussebab, also in Sirnak province, security officials said. PKK militants scrapped a unilateral cease-fire last week following an increase in violence. Almost 40 soldiers have been killed in the past two months, according to media reports. Sunday, the Turkish army intensified cross-border shelling of the Zap region of northern Iraq, where the PKK is mainly based, from sites in Sirnak and Hakkari provinces, the sources said. The PKK took up arms against the Turkish state in 1984, and more than 40,000 people, mainly Kurds, have been killed in the fighting. Prime Minister Tayyip Erdogan has pledged to expand the cultural and political rights of Kurdish citizens to try to end the conflict. Kurds make up about 20 percent of Turkeys population of 71 million.