An Istanbul policeman went on trial on Wednesday charged with shooting dead a 25-year-old Turkish woman suspected of links to far-left activists during an "anti-terror" raid in the city.

Prosecutors have asked for 26.5 years jail for the officer, named only as Y.M., over the killing of Dilek Dogan in the raid on her family home in the Sariyer district on October 18.

She died of her wounds in hospital on October 25. Turkish media later published harrowing footage of the moment her family realised she had been shot.

The case has won huge resonance with the police under scrutiny over allegedly heavy-handed tactics employed in a massive crackdown against Islamist, Kurdish and Marxist militant groups.

The trial got underway amid a heavy security presence at the Istanbul courthouse with Dilek Dogan's mother, father and brother all present, the DHA news agency said.

At least 22 people were detained when police used water cannon to break up a group of supporters of the family who sought to enter the courthouse without authorisation, reports added.

Dogan's parents have claimed their daughter is an innocent victim and so far no concrete evidence has been put forward linking her to attacks.

They say she was killed after the policeman drew his weapon when she yelled at the anti-terror squad to put on overshoes so as to not dirty the floor.

The police have said the gun was fired in a scuffle after the family tried to snatch it away.

Media reports have said the authorities suspected her of membership in the Revolutionary People's Liberation Party-Front (DHKP-C), links to a gun attack on the US consulate in Istanbul and possible involvement in plans for a suicide bombing in the city.

The authorities have been cracking down on the DHKP-C, which has staged a sporadic series of attacks in Turkey in the last years, as part of a broad anti-terror operation also aimed at Islamic State (IS) and Kurdistan Workers Party (PKK) members.

Turkish media reports Tuesday also said a separate investigation had been launched against her father Metin, her mother Aysel and her brother Mehmet on accusations of impeding the police officers in their work during the raid.