The jailed leader of Peru's Shining Path rebel group and his girlfriend say they will go on hunger strike unless they are allowed to wed.
Abimael Guzman and Elena Yparraguirre are both serving life sentences.
Their lawyer said they had been asking for permission to marry for several years and were tired of waiting.
The Mao-inspired Shining Path unleashed a brutal civil conflict in the 1980s and 1990s in Peru, in which nearly 70,000 people were killed.
They may be the most reviled couple in Peru but they maintain they have the right under law to have their relationship formalised by marriage.
Their lawyer, Alfredo Crespo, said the pair "have decided that if [the government] does not bring them the documents by Monday, the both of them will start a hunger strike on Tuesday".
Under Peruvian law, prisoners can marry and are even allowed several conjugal visits a year.
But the couple's plea seems beset by the usual bureaucracy and is not helped by the fact that they had both been married to other people.
Mr Guzman is now widowed and Ms Yparaguirre left her husband more than 30 years ago to join the Shining Path.
Earlier this year, President Garcia said he saw no reason why Mr Guzman - despite being the most despicable criminal in Peruvian history - could not marry.
Yet it seems clear that Peruvian officialdom is reluctant to rubberstamp the nuptials.
Abimael Guzman, the founder of the Shining Path, was captured in 1992, along with his second-in-command Ms Yparaguirre.
The self-declared armed struggle officially ended there.