ATHENS — A hospital in central Greece said Friday a far-left militant convicted of 11 murders is in critical condition after suffering kidney failure following 56 days of hunger strike.

Dimitris Koufodinas, who is serving 11 life sentences for his role in the November 17 group, began the protest on Jan. 8, arguing that a prison transfer in December occurred in violation of his rights as an inmate.

November 17, which mixed Marxism with nationalism, killed 23 people, including U.S., British and Turkish diplomats, between 1975 and 2000. It was eradicated following a string of arrests in 2002 and subsequent convictions. 

Authorities earlier this week increased security at police department buildings and other potential targets, in preparation for possible violent reprisals if Koufodinas dies. Several buildings housing government departments and offices of politicians have already been recently vandalized and targeted in arson attacks by supporters of Koufodinas.

The 63-year-old is being treated in intensive care at a hospital in Lamia, some 215 kilometers (130 miles) north of Athens.

The government has denied Koufodinas' request, which was being heard in a renewed petition from his lawyers in a regional court Friday.

Koufodinas' demands have been backed by near-daily public protests in Athens and other cities, but a recent opinion poll suggests that nearly 70% of Greeks oppose his demand.