Prime Minister Sheikh Hasina called for calm after at least four people were killed when police fired on thousands of Bangladeshi Muslims protesting Facebook messages that allegedly defamed the Prophet Mohammed.Mob attacks over online posts perceived to be blasphemous have emerged as a major headache for security forces in Bangladesh, where Muslims make up some 90 percent of the country’s 168 million people. Some 20,000 Muslims demonstrated at a prayer ground in Borhanuddin town on the country’s largest island of Bhola to call for the execution of a young Hindu man charged with inciting religious tension through online messages. Police said they opened fire in self-defence after some of the crowd threw rocks at officers.Prime Minister Hasina said the Facebook account of the man charged with inciting religious tension was hacked by a Muslim person and used to “spread lies”. Bhola’s deputy police chief Sheikh Sabbir revealed that the man came to the police station on Saturday, claiming his Facebook account was hacked.“We also suspect that his account was hacked and these contents were spread through Facebook messenger,” he said. However, the charges have not been dropped.In 2016, angry Muslims attacked Hindu temples in an eastern town over a Facebook post that allegedly mocked one of Islam’s holiest sites.In 2012, Muslim mobs torched Buddhist monasteries, houses and shops in the coastal Cox’s Bazar district following a Buddhist youth’s alleged defamatory photo post of the Koran.Notably, Bangladesh has also experienced a number of attacks on people from religious minorities, secular bloggers, publishers, writers and foreigners, many claimed by Islamist militants.