Turkish police on Friday raided the offices of the main pro-Kurdish party in central Istanbul, making arrests and seizing documents.

Turkish police on Friday raided the offices of the main pro-Kurdish party in central Istanbul, making arrests and seizing documents.

Riot police blocked the entry to the street where the Beyoglu district office of the Peoples' Democratic Party (HDP) is located while anti-terror police conducted a search, an AFP photographer said.

Turkish media reports said that several people were detained in the two-hour operation, including the co-chair of the Beyoglu branch of the HDP, Rukiye Demir.

The authorities have stepped up legal pressure on the HDP as the military wages a relentless campaign to flush out Kurdish militants from inside towns in the southeast.

Prosecutors have launched investigations against the co-leaders of the HDP -- Selahattin Demirtas and Figen Yuksekdag -- and President Recep Tayyip Erdogan has called for their parliamentary immunity to be removed.

The authorities accuse the HDP of acting as the political arm of the outlawed Kurdistan Workers Party (PKK), classified a terror group by Turkey and its Western allies. The HDP vehemently denies this.