"The Turkish Armed Forces cannot accept anything that might harm the unified structure of the state," the chief of general staff, General Ilker Basbug, said in an online message.

He ruled out contacts with members and followers of the "terrorist organisation", referring to the rebel Kurdistan Workers' Party (PKK), which has waged a bloody 25-year separatist campaign in southeast Turkey.

Turkey's army, he said, "respects cultural diversity," but stressed that Turkish should remain the country's sole official language.

His message was posted to mark the anniversary of Turkey's victory over Greek troops in August 1922.

Prime Minister Recep Tayyip Erdogan's government has said it is working on fresh reforms to expand Kurdish freedoms in a bid to erode popular support for the PKK.

Kurdish activists argue the conflict cannot be resolved if the PKK is overlooked and if Ankara fails to draw up a clear strategy to convince the rebels to lay down their arms, including a general amnesty.

New air force commander Hasan Aksay vowed Tuesday that the military would continue to fight the PKK "until the last terrorist is eliminated."

"The armed struggle against the terrorist organisation... is continuing resolutely, without concessions and with an increasing force," he said.

The government has remained tight-lipped on the content of the reform plan, while struggling to win support from civic groups and a hostile opposition which argues broader Kurdish rights will threaten Turkey's unity.

A senior ruling party lawmaker said last week the Kurdish language could be introduced as an elective course in Turkish schools as part of the plan.

According to media reports, the government may also consider returning the Kurdish names of villages that have been renamed, lifting a ban on using Kurdish in political propaganda and modifying the definition of Turkish nationality in the constitution.

Keen to boost its bid to join the European Union, Turkey has in recent years granted the Kurds a series of cultural liberties, including the launch of a public Kurdish-language television channel.

But Ankara has failed to cajole the PKK into laying down arms and thousands of militants remain holed up in mountainous bases in southeast Turkey and neighbouring northern Iraq.

The PKK, listed as a terrorist group by Ankara and much of the international community, took up arms for Kurdish self-rule in the southeast in 1984, sparking a conflict that has claimed about 45,000 lives.