Greece's public order minister is offering a reward of about four million euro (£3.3 million) for information leading to the capture of fugitive terrorists.
Nikos Dendias said the details would be announced later in the day. He did not specify how many fugitives the reward would concern.
Greek authorities have been conducting a nationwide manhunt since January 7 when Christodoulos Xiros, a 55-year-old serving six life sentences for carrying out killings as part of the November 17 group, vanished while on release from prison.
He appeared in a video posted on the internet on Monday vowing a return to attacks.
In 2012, a married couple suspected of belonging to another militant group vanished following their release from jail after serving the maximum 18 months in pre-trial detention.