ISTANBUL: Turkish police fired tear gas and water cannon at protesters in Istanbul staging a demonstration in support of a widespread hunger strike by Kurdish prisoners, an AFP photographer at the scene said.

Around 400 protesters were gathered outside the Kurdish Peace and Democracy Party (BDP) building, chanting "Evacuate prisons" and "Freedom to inmates", when police fired the tear gas and water cannon without warning, the photographer said.

The group also shouted slogans in favour of the imprisoned leader of the banned Kurdistan Workers' Party (PKK) Abdullah Ocalan.

The Turkish government is under increasing pressure over how to tackle the hunger strike by around 700 Kurdish prisoners which is now in its 54th day.

The strike involves jailed politicians, mayors and parliamentarians, some of them senior figures in the BDP, which holds 29 of the 550 seats in the Turkish parliament, and also inmates accused of ties to the PKK.

The strikers are calling for the lifting of restrictions on the use of Kurdish language but their main demand is improved jail conditions for Ocalan, who is imprisoned on an island off Istanbul.

On Saturday, Prime Minister Recep Tayyip Erdogan warned hunger strikers against "blackmail" for the release of Ocalan, saying: "We will not release the terrorist chief just because you say so or resort to such an action."