"The EU's aid to Eritrea must gradually be halted," said the heads of the Swedish chapters of rights groups like Reporters Without Borders and PEN, along with journalist and publishing associations in a statement to mark World Press Freedom Day.
No aid should be given to Asmara "until the Eraeiro death camp is closed, its prisoners are given medical care ... and released or given an open trial on the 'crimes' they are suspected of," they wrote in an opinion piece in the Dagens Nyheter daily.
According to the piece, the EU's total aid package to Eritrea in coming years totals $413 million.
Their appeal came amid new reports on harsh conditions at the high-security Eraeiro secret prison near Asmara, where Swedish-Eritrean journalist Dawit Isaak and a number of other reporters and opposition politicians are reportedly being held.
An Eritrean with Swedish citizenship, Isaak was arrested in September 2001 along with a dozen newspaper owners, editors and journalists accused of being Ethiopian spies.
A number of demonstrations were planned across Sweden Monday calling for the release of the reporter, now 45.
"The prisoners are dying one by one. How long will it take before the world reacts and puts pressure on Eritrea to release the political prisoners?" Isaak's brother Esayas told the TT news agency.
Last month, the first information in years pinpointing Isaak's whereabouts and describing the conditions of his detention emerged in Sweden, and on Monday new accounts from a former guard at the Eraeiro prison surfaced.
Isaak "complains all the time, asking for 'medicine, medicine,' and all the time asking for help from a doctor ... I think he has mental problems," ex-guard Eyob Bahta Habtemariam told the Expressen daily.
Habtemariam, in hiding in Ethiopia, said he had last seen Isaak on January 5th, right before he himself fled from Eritrea.
He said Isaak was held handcuffed nearly around the clock in solitary confinement in a windowless cell measuring only 12 square metres at the secret prison, some 50 kilometres from Asmara.
The prisoners there, which include former government ministers opposed to President Isaias Afeworki, were not tortured, but according to Habtemariam, the suffocating heat and isolation "was worse than torture".
"When I started working (at the prison) nine years ago, there were 35 prisoners. Fifteen of them are dead today," he told Expressen, adding that three of the dead had killed themselves.
"There is a risk (Isaak) will kill himself," Habtemariam insisted.