DHAKA (Reuters) - At least four people were killed and about 50 others injured on Sunday in clashes with police in Bangladesh over an offensive Facebook post, officials said.

The clashes erupted in the southern Bhola district, 195 km from the capital Dhaka, after angry crowds protested after reports of a Hindus posting a Facebook post that insulted the Prophet Muhammad.

"We fired empty shots in self-defense, but some people started throwing stones at our people, which led us to take shelter in a building," said Bhola Sarkar police official Mohammad Qaisar.

Four people were killed and a policeman was shot in the clash, he said. Border guards and police reinforcements were sent to Bhola.

Sheikh Hasina asked citizens to be patient (Reuters)

Call for calm
Bangladeshi Prime Minister Sheikh Hasina on Sunday called for calm, noting that the account of the man accused of stirring up sectarian strife on Facebook was hacked by a Muslim and used to "spread lies."

"We have seen rumors on Facebook to create an environment of chaos. Who are they? What are their intentions?" She said in a speech to members of her political party.

"I have asked our citizens to be patient. Those who want to fish in troubled waters will find them and take measures against them."

Bhola's deputy police chief said the man had come to the police station on Saturday and had reported a hacking of his Facebook account.

"We also suspect that his account has been hacked and these contents were published via Facebook Messenger," but the charges have not been dropped.

The attacks, which came against the backdrop of blasphemy Facebook comments, force security forces in Bangladesh, where 90 percent of the country's 168 million people are Muslims.

This is not the first time the country has witnessed violence following Facebook comments deemed religiously provocative.

In 2016, angry Muslims attacked Hindu temples in the east of the country against the backdrop of a Facebook post they considered making fun of Muslim holy cities.

In 2012, gangs of Buddhist monasteries, houses and shops in the Cox's Bazar area burned down against the background of a Buddhist youth on Facebook posting a picture deemed offensive to the Koran.

Bangladesh has witnessed a number of attacks on religious minorities, secular bloggers, publishers and foreigners, many of whom have been adopted by Islamists.