ISTANBUL (AFP) - Turkish authorities arrested 23 more people on Saturday over their alleged role in this month's anti-government protests, accusing them of acting on behalf of a far-left "terrorist" group, a news report said.

A court in the capital accused them of helping to organise the protests and engaging in violence in the name of the Communist Marxist-Leninist Party (MLKP), CNN-Turk said on its website.

Another three were released but placed under judicial supervision, the report said.

Interior Minister Muammer Guler said the operation had been planned for about a year against the "terrorist" (MLKP), but that the suspects were also implicated in the protests, the most violent since Prime Minister Recep Tayyip Erdogan's Islamist-rooted government came to power in 2002,.

Prosecutors could not immediately confirm the arrests, which follow a sweep last Tuesday against far-left groups in Ankara and Istanbul and bring to at least 47 those detained over the protests that grew from a peaceful demonstration on May 28.

In Istanbul, 18 members of the small far-left Socialist Party of the Oppressed (ESP) were detained in the same operation on Friday and held for "belonging to a terrorist organisation" and "destroying public property".

On Tuesday, police had arrested dozens of ESP members and searched the offices of the Atilim newspaper and the Etkin news agency, both tied to the group.

What began as a peaceful protest against plans to demolish Istanbul's Gezi Park, one of the city's last large green spots, turned violent on May 31 when police used tear gas and water cannon to disperse demonstrators.

Police moved in on June 15 to evacuate Gezi Park, the last stronghold of the anti-government protesters after a series of police crackdowns. The protests claimed at least four lives and left thousands injured.