DIYARBAKIR, Turkey, July 17 (Reuters) - Two Turkish soldiers have been killed in a clash with Kurdish separatist rebels during a military offensive in southeast Turkey, a regional governor's office said on Tuesday.

The two men died on Monday in mountainous Sirnak province after the guerrillas ignored a call to surrender and opened fire, the Sirnak governor's office said in a statement.

The military ground operation is continuing in the area, backed by helicopters, the statement added.

The clash comes just days before a national election in Turkey in which an increase in Kurdish rebel attacks has been a major theme.

Turkish nationalists demanding much tougher measures against the outlawed Kurdistan Workers Party (PKK) are expected to perform well in Sunday's election.

Turkey's centre-right government, which is tipped to remain in power, has repeated calls in recent days on the United States and the Baghdad government to crack down on PKK fighters who use bases in northern Iraq to attack targets inside Turkey.

Ankara blames the PKK for the deaths of more than 30,000 people since the group launched its armed campaign for an ethnic homeland in southeast Turkey in 1984. Violent attacks have increased over the past year.

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