Four soldiers killed in blast in eastern Turkey

(Adds details, background)

DIYARBAKIR, Turkey, Aug 17 (Reuters) - Four Turkish soldiers were killed and three wounded on Monday in an explosion during a training exercise in the eastern province of Elazig, security sources said.

The blast occurred when a hand grenade being carried by one of the soldiers exploded during a patrol in the district of Karakocan at around 1 pm (1000 GMT), the sources said.

An investigation into the incident was under way.

Turkey's military is engaged in a conflict in southeast Turkey with separatist Kurdistan Workers Party (PKK) militants.

Some 40,000 people have been killed in fighting between the PKK and the military since 1984, when the PKK took up arms with the aim of establishing an ethnic homeland in southeast Turkey. (Writing by Daren Butler; Editing by Richard Balmforth)