Over recent days, the two men, aged 49 and 38, sentenced to six years and ten months and 21 years respectively, were found dead in their cells.
One was found lifeless and the other hanged.
A European study released in March this year found that the average death rate in Portuguese prisons was 43.4 per 10,000, with a suicide rate of 9.1 prisoners per 10,000 in 2013. An American report found that overcrowding in Portugal’s jails last year posed a human rights problem.