DIYARBAKIR, Turkey (REUTERS) - Six people were killed on Sunday in clashes between groups backing rival candidates in Turkey's municipal elections, which turned into a referendum on the rule of Prime Minister Tayyip Erdogan.

Security officials said four people were killed in a gun fight between two families in the village of Yuvacik in the eastern province of Sanliurfa, which borders Syria. Such clashes have occurred at previous local elections.

In Hatay province, also bordering Syria, two people died in a gunbattle between relatives of two candidates in Golbasi village, the officials said. Candidates in the voting for these local officials are not party-affiliated.

Tensions rose in Turkey in the build-up to the elections, with Erdogan trying to fight off graft allegations and stem a stream of damaging security leaks.