ANKARA, (Reuters) – Turkish warplanes fired on a group of Kurdish guerrillas in northern Iraq on Tuesday as they tried to enter Turkey, the General Staff said on Wednesday.

The General Staff said in a statement the warplanes “neutralised”, generally meaning killed, the Kurdistan Workers’ Party (PKK) rebels in the Avasin-Basyan region of northern Iraq.

Ankara says thousands of separatist PKK rebels use a remote, mountainous part of northern Iraq as a base from which to stage attacks on targets inside Turkey.

Turkey staged an eight-day ground incursion against the PKK in February, sending thousands of troops into Iraq. The General Staff said 240 rebels were killed in the campaign, along with 27 of its own men.

That operation prompted concern in Washington about further regional instability and was watched closely in Turkey’s financial markets.

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.

Turkey, like the European Union and the United States, considers the PKK a terrorist organisation.

Turkish authorities usually step up their operations against the PKK in spring to prevent rebels crossing into Turkey when weather conditions improve.

The General Staff said operations were continuing in southeast Turkey with two separate clashes on April 15. It said one rebel had been killed.

Various weapons and equipment used in making explosives were seized during these clashes, the statement said.

Turkish Prime Minister Tayyip Erdogan pledged last month that his government would invest up to $12 billion in southeast Turkey over a five-year period in an effort to drain support for the PKK. The government has pledged to allow a state television channel to broadcast in the Kurdish language.

The EU, which Turkey hopes to join, has long urged Ankara to remove restrictions on the Kurdish language and culture.