Gulser Yildirim and Ibrahim Ayhan are accused of being members of the urban wing of the Kurdistan Workers' Party (PKK), listed as a terrorist group by Ankara and much of the international community.

They were among six Kurdish politicians awaiting trial for terror-related charges who were elected to parliament in the June 12 elections as independent candidates from the mainly Kurdish southeastern Anatolia region.

Three of them were denied release from prison Saturday, while one, Hatip Dicle, had been stripped of his seat over a recently upheld terror-related conviction.

Police Sunday used tear gas and water cannons to disperse hundreds of demonstrators, protesting the rulings in downtown Istanbul, according to an AFP photographer at the scene.

Protestors gathered in the central Sisli district and wanted to march nearby Taksim square, as police blocked their way. Among the demonstrators were independent deputies, who were elected to parliament from Istanbul.

The court rejected pleas for the deputies' release on the grounds that terror-related charges fall out of the scope of parliamentary immunity, and the deputies might change evidence, put pressure on witnesses or flee if they are released, Anatolia news agency reported Sunday.

In the June 12 elections, Turkey's main political movement Peace and Democracy Party supported independent candidates to overcome the 10 percent election threshold and managed to sent totally 36 deputies to parliament.

Earlier this week judges rejected similar pleas for journalist Mustafa Balbay, academic Mehmet Haberal and retired general Engin Alan, who are accused of involvement in alleged plots to destabilise and overthrow Turkey's Islamist-rooted government.

Balbay and Haberal was elected to parliament on the ticket of the main opposition Republican People's Party, while Alan won the ballot from Turkey's second main opposition force, the Nationalist Action Party.

Turkey's new parliament is braced for a tense opening this week after some 30 Kurdish lawmakers announced Thursday they would boycott the legislature in protest at the controversial ruling stripping Dicle of his seat.

The PKK took up arms in southeast Turkey in 1984, sparking a conflict that has claimed about 45,000 lives.