DIYARBAKIR, Turkey, Aug 31 (Reuters) - Turkish police in the mainly Kurdish southeastern city of Diyarbakir fired into the air to disperse up to 3,000 people chanting slogans on Friday in support of Kurdish rebel leader Abdullah Ocalan.

Protesters hurled stones at police, who advanced with batons or took cover behind riot shields. Security forces told Reuters 15 people, including three police, had been wounded.

The crowd had gathered in the city centre, preparing to board buses to travel to the capital Ankara for a demonstration planned for Saturday by the country's only legal Kurdish party, the Kurdish People's Democratic Party (HADEP).

The demonstration by HADEP, facing a possible ban over charges that it serves separatist Ocalan's guerrillas, aimed to bring 100,000 people together from all around the country.

The Interior Ministry has refused permission for the rally, but activists still plan protests.

World Peace Day on September 1 has become a traditional protest day for Kurdish activists who seek cultural rights, or independence, for Turkey's 12 million Kurds. Immediate demands include use of Kurdish language in education and broadcasting.

They also want the death penalty to be scrapped. Kurdistan Workers Party (PKK) leader Ocalan was sentenced to death for leading a campaign for Kurdish self-rule that cost over 30,000 lives.

He is now jailed on a Turkish island and awaiting the result of his appeal to a European Court.

Turkish authorities see "Apo's" call after a 1999 death sentence for a switch to peaceful political campaigning as a ruse to escape the noose and refuse to negotiate with the PKK.

"Police intervened when the crowd began shouting 'Long live Apo, long live peace, long live the PKK'," an eyewitness said.

Police later fired into the air and the protesters withdrew to nearby narrow streets.

Violence has declined markedly in the region over the last two years, but there is little sign of political progress in defusing remaining tensions. Several major cities in the area have elected HADEP mayors.