The nine suspects of Kurdish origin -- eight men and a woman -- were charged with participation in a terrorist group, terrorist acts inducing bomb-making and possession of arms and explosives, a judicial source said.

They are thought to be members of the Marxist Revolutionary People's Liberation Party-Front (DHKP-C), branded a terrorist organisation by Turkey and its Western allies.

Greek police minister Nikos Toskas on Tuesday said "until now" there was no evidence that the suspects were planning an attack on Erdogan, who is due to visit on December 7-8.

The nine are not cooperating with the authorities, the minister told Antenna TV.

They were arrested following raids on Tuesday on three apartments near the centre of the Greek capital, according to a police source.

Officers found a pistol, detonators, materials that could be used in bomb construction, and passports.

One of the suspects had been sought since 2013, when a speedboat carrying weapons was intercepted off the island of Chios, apparently sailing to Turkey.

For many decades members of Kurdish organisations have fled to hide in Greece, which has delicate relations with neighbouring Turkey because of territorial differences.

Turkey is also unhappy that Greece has failed to extradite suspects wanted over the 2016 failed coup, notably eight officers who escaped by helicopter on the putsch night.

However, the two countries are cooperating over the migrant crisis, following a deal between Turkey and the EU which has significantly stemmed the flow of people to Europe.

Erdogan's visit is the first to NATO ally Greece by a Turkish head of state in 65 years.