ATHENS -- Greek police were poised on Sunday to make arrests and name names after swooping on two safe-houses in a narrowing search for followers of a shadowy guerrilla group blamed for killing 23 people since 1975.

"Some time today or tomorrow there will be official announcements about arrests of about six or seven people in the next phase of our operation against the November 17 terrorists," a top police source, who did want to be named, told Reuters.

Authorities have described this week's raids as their biggest breakthrough in hunting down November 17, which staged its first attack by assassinating the CIA station chief in Athens 27 years ago.

Its most recent victim was British Military Attache Stephen Saunders, gunned down in 2000 as part of the radical leftist group's proclaimed fight against capitalism.

Greek media have reported that U.S. and British investigators have played a role in this week's searches, which followed the detention of a man in a botched bombing.

The group, named after the date in 1973 of a student uprising against Greece's military junta, has survived until now unscathed while other radical contemporaries, like West Germany's Baader Meinhoff gang and the Italian Red Brigades, have disappeared into history.

The police source said the first formal warrant would probably be for the arrest of the 40-year-old man injured in the botched bomb blast a week ago at Athens' port of Piraeus, who is under guard in hospital.

Police consider him the first November 17 suspect detained in a decades-long hunt for the group, who used rockets, remote-controlled bombs and drive-by assassinations.

Authorities have questioned dozens of friends and relatives of suspect Savas Xyros, an icon painter and son of a priest.

A raid on Saturday, which brought traffic in central Athens to a standstill, was announced just hours after police were able to quiz the badly injured Xyros for the first time.

The police source said a second man was also in custody as a result of that raid on an Athens apartment where a cache of anti-tank rockets, bombs, police uniforms and wigs were found.

A first raid on Wednesday on another apartment yielded a similar haul including about 100 rockets and other weapons stolen from Greek military bases in the 1980s.