Turkey's military chief has warned of threats to the country's secular system, one day before a candidate from the Islamic-rooted ruling party is expected to be elected president.

General Yasar Buyukanit (file photo)

General Yasar Buyukanit, head of the staunchly secularist military, said in a statement Monday that "centers of evil" are trying to undermine Turkish secularism.  He said the military will protect Turkey's secular and democratic structure.

Tuesday, parliament is expected to elect Foreign Minister Abdullah Gul as president.  He is the candidate of the ruling Justice and Development party.

Turkey's secularists fear Gul, a devout Muslim, will undermine constitutionally enshrined secular principles, but Gul has pledged to uphold secularism.

Prime Minister Recep Tayyip Erdogan has warned the military not to get involved in politics.

Gul failed to win a two-thirds majority in the first two rounds of voting for president, but only a simple majority is required in Tuesday's third round.

Gul's wife wears an Islamic headscarf, which has been banned in Turkey's public offices and schools since a 1980 military coup.

His nomination for president earlier this year sparked a political crisis in which thousands of secularists took to the streets to protest his candidacy. The military threatened to intervene to protect Turkey's secular system.