Human Rights Watch has called on the Egyptian authorities to stop persecuting people for atheism, after a student received a three-year jail term for Facebook posts that allegedly insulted Islam.

The New York-based group said the sentence handed down on blasphemy charges were part of a "coordinated government crackdown on perceived atheists."

“Atheists are one of Egypt’s least-protected minorities, although the constitution ostensibly guarantees freedom of belief and expression,” said Sarah Leah Whitson, Middle East and North Africa director at Human Rights Watch.

“Egyptian authorities need to be guided by the constitution and stop persecuting people for atheism.”

On Sunday, 21-year-old Karim El-Banna was found guilty, after his own father testified against him, and was sentenced to three years with a bail of 1,000 Egyptian pounds ($140 or 117 euros), AFP reported.

According to a researcher with the Egyptian Initiative for Personal Rights (EIPR) Ishaq Ibrahim, Banna was arrested when he went to file a complaint against his neighbours who harassed him after his name had appeared in a list of known atheists in a local daily.

Banna, in custody since November, was accused of insulting Islam, Ibrahim, who has been tracking the case, told AFP.

According to EIPR statistics, revealed to HRW, Egyptian courts convicted 27 of 42 defendants on charges of contempt for religion from 2011 to 2013. Judges acquitted three defendants and rejected charges against 11 others for lack of standing.

In mid-December, the head of Cairo’s Abdeen district headed a police raid against what he called an “atheist cafe” and closed it down.

"Egypt is party to human rights treaties, including the International Covenant on Civil and Political Rights and the African Charter on Human and Peoples’ Rights, which require its government to respect and protect freedom of religion and belief and freedom of expression, without any discrimination," HRW said, stating different cases of blasphemy persecutions.