(Adds fresh attack, changes dateline, previous Diyarbakir)

TUNCELI, Turkey, May 9 (Reuters) - Turkish military sources said at least 20 Kurdish separatists and two Turkish soldiers were killed after Kurdistan Workers Party (PKK) guerrillas attacked a military base in southeast Turkey late on Friday.

Turkish warplanes bombed rural areas along Turkey's border with Iraq after some 50 PKK members from northern Iraq attacked a gendarme station near the border, killing two soldiers.

The bombings killed 20 militants, the military sources said. No further details were available.

Earlier in the day three people were killed and a dozen injured in a series of explosions in the region blamed on the Kurdish separatist guerrillas.

The three landmine blasts, set off by remote control, were in the southeastern provinces of Siirt and Batman and in eastern Bingol province, said security sources, who declined to be named.

The violence comes amid an ongoing military operation, backed by attack helicopters, tanks and artillery against separatist Kurdistan Workers Party (PKK) guerrillas in the restive and mountainous parts of southeast Turkey.

Amid widespread public anger over PKK attacks, Turkey has sent tens of thousands of troops to the border region. Over the week dozens of Turkish F-16 warplanes have also gone on bombing raids against suspected PKK positions deep inside neighbouring northern Iraq.

Turkey blames the PKK for the deaths of nearly 40,000 people, mostly Kurds, since the group began its armed campaign for an ethnic homeland in southeast Turkey in 1984.

President Abdullah Gul said on Friday the military's latest air strikes against the rebels in northern Iraq were among the most significant blows yet against the separatist movement.

"I can say we are in an important period in terms of Iraq and the struggle with the PKK," Gul told reporters during a Europe Day reception in Ankara.

Turkey says several thousand PKK rebels use a remote, mountainous part of northern Iraq as a base from which to stage attacks on targets inside Turkey. Iraqi authorities say they are keen to cooperate with NATO member Turkey but complain that they have no control over the isolated part of the oil-rich country.

The tensions over the PKK, considered a terrorist organisation by the United States, Turkey and the European Union, in northern Iraq has helped boost global oil prices.

The Turkish military said on Saturday it had killed more than 150 PKK members in air strikes in May. The rebel group denied this.

Thousands of Turkish troops conducted an eight-day large-scale incursion into Iraq in February in which the military said it killed 240 guerrillas and lost 27 of its own men.

SERIES OF BLASTS

The PKK's landmine attacks caused the first civilian casualties suffered within Turkey for months, reminiscent of a series of attacks that led up to the military's first threats last autumn of a cross-border operation into Iraq.

One of those killed in the explosion was a village teacher.

"Our assessment is that the explosion, which targeted a minibus carrying villagers, was remotely detonated. We have sent a helicopter to the site," Batman governor Recep Kizilcik told Reuters.

He said members of the state "village guard" militia were travelling in the minibus.

The PKK, which still attracts strong support in mainly Kurdish southeast Turkey due to economic hardship and perceptions of political repression, frequently plants mines targeting security forces.

In a separate attack, a military officer and a member of a village guard militia were injured in a landmine blast in Siirt province. In another attack, an officer and two other soldiers were injured while on patrol when a landmine planted by PKK exploded under their vehicle in Bingol province, security sources said. (Additional reporting by Zerin Elci in Ankara and Daren Butler in Istanbul; writing by Paul de Bendern and Thomas Grove; Editing by Charles Dick)

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