DIYARBAKIR, Turkey (Reuters) - Ten members of the separatist Kurdistan Workers Party (PKK) were killed in clashes with Turkish military forces in southeastern Turkey late on Friday, security sources said on Saturday.

Six were killed in the firefight which broke out in a rural region of Siirt province after Kurdish guerrillas detonated an improvised explosive device under a minibus carrying schoolchildren, injuring two people.

Security forces said the clashes began after they launched an operation to find the group responsible for the attack.

They also said two PKK members were killed in a clash in Hakkari late on Friday and two other militants were killed in Bingol.

Nearly 50 members of the separatist PKK and six soldiers have been killed this week.

More than 40,000 have been killed since 1984 when the PKK took up arms to carve out an ethnic homeland in primarily Kurdish southeast Turkey.

Turkey considers the PKK a terrorist organization, as does the European Union and the United States.