By Seyhmus Cakan and Ayla Jean Yackley
DIYARBAKIR, Turkey (Reuters) - Roadside bombs killed at least six people in two separate attacks on security forces in Turkey's largely Kurdish southeast on Monday, security sources said, adding to the violence that has flared across the region in the last 24 hours.
One bomb hit a passing police vehicle in the town of Silopi in Sirnak province near the border with Iraq, the sources said, hours after Turkish warplanes struck camps belonging to the outlawed Kurdistan Workers Party (PKK) in northern Iraq.
Four civilians were killed and 19 other people were injured, including five security force members, in that attack, the sources said. Turkey's Dogan News Agency said the bomb had been placed inside a manhole and was detonated as a police vehicle passed.
Earlier, near the eastern city of Van, PKK fighters detonated a roadside bomb by remote control targeting a passing armored vehicle. Two police officers were killed and a third was wounded, the sources said.
Clashes between Turkish security forces and the PKK have reached their most intense in two decades since the breakdown of a two-year ceasefire last July.
Thousands of militants and hundreds of civilians and soldiers have been killed since the PKK resumed its armed fight. The government has refused to return to the negotiating table and has vowed to "liquidate" the PKK, considered a terrorist organization by Turkey, Europe and the United States.
Late on Sunday, PKK snipers attacked a Turkish base located inside Iraq, killing a lieutenant, the sources said. In the past Turkey has garrisoned a battalion in Iraq's Kani Masi region to prevent PKK fighters from crossing into Turkey.
A man suspected of smuggling goods across the border between Iraq and Turkey was killed and five others injured, when unidentified forces opened fire on smugglers across the border in the Uludere district, they said.
Uludere was the site of an airstrike in December 2011 that killed 34 young men and boys after the military mistook them for PKK militants. Smuggling of cigarettes, fuel and household items is widespread in the poverty-stricken border region.
The PKK also attacked a base in the Turkish town of Siirt, killing one soldier, the military General Staff said. A police officer was also killed in Sirnak province, under a round-the-clock curfew since March 14, security sources said.
In the village of Kulp in Diyarbakir province, a civilian and five members of the village guard, a state-backed militia that fights the PKK, were wounded in a car-bomb attack, they also said.
The General Staff said on its website it had destroyed PKK shelters and weapon stores in the Metina area of northern Iraq on Sunday during the air strikes. It gave no casualty count.
The PKK has been based in the remote, mountainous region of northern Iraq, which borders southern Turkey, since the 1990s. The PKK launched its insurgency against the Turkish state in 1984 and more than 40,000 people have been killed in the conflict.
(Reporting by Seyhmus Cakan; Writing by Daren Butler and Ayla Jean Yackley; Editing by Richard Balmforth)