A recent study shows 13 Muslim countries carry out executions under the law when people openly embrace atheism or reject the official state religion of Islam, according to a detailed study issued on Tuesday.

Apart from the Islamic nations, some of the West's most democratic governments at best discriminate against citizens who have no belief in a god and at worst can jail them for offences dubbed blasphemy, Reuters reported.

The study from The Freethought Report 2013, was issued by the International Humanist and Ethical Union (IHEU), a global body uniting atheists, agnostics and other religious skeptics, to mark United Nations' Human Rights Day on Tuesday.

"This report shows that the overwhelming majority of countries fail to respect the rights of atheists and freethinkers although they have signed U.N agreements to treat all citizens equally," said IHEU President Sonja Eggerickx.

According to Reuters, the IHEU said there was systematic or severe discrimination against atheists across the 27-nation European Union.

Consisting of lawyers and human rights experts who looked at statute books, court records and media accounts to establish the global situation, the study covered all 192 member states in the world body, Reuters reported.

An earlier survey of 60 countries last year showed just seven countries where death, often by public beheading, is the punishment for either blasphemy or apostasy - renouncing belief or switching to another religion which is also protected under U.N. accords.

Across the world, the report said, "there are laws that deny atheists' right to exist, revoke their citizenship, restrict their right to marry, obstruct their access to public education, prevent them working for the state...."

The report asserted that criticism of religious faith or even academic study of the origins of religions is frequently treated as a crime and can be equated to the capital offence of blasphemy.

According to Reuters, in India, in a recent case involving a leading critic of religion, humanists say police are often reluctant or unwilling to investigate murders of atheists carried out by religious fundamentalists.

In the United States, the report said, although the situation was "mostly satisfactory" in terms of legal respect for atheists' rights, there were a range of laws and practices "that equate being religious with being American."