At least five persons have been killed and dozens injured as police in Bahrain opened fire at supporters of the country's prominent Shia cleric, Ayatollah Isa Ahmed Qassim, officials said.

Over 280 Isa Qassim supporters were also detained during the police action in Duraz, about 15 km from here, on Tuesday, as they protested against his imprisonmenet, Efe news reported.

The indicted cleric's followers fought back with "hand grenades, iron bars, and bladed weapons and axes, which resulted in the injury of 19 security men," Bahrain's Interior Ministry said in a statement.

The 286 people arrested, included terror "fugitives" who had managed to escape from Jau prison, the officials said.

"It is unfortunate that these young people fall victim to these acts, which are incited from abroad," the Interior Ministry added.

In a statement, the Human Rights Watch NGO, however, described the operation as a "strategic show of strength aimed at ending a peaceful and legitimate protest".

The NGO said the violence by the Al Khalifa government raised questions as it came two days after King Hamad's meeting with US President Donald Trump. 

Isa Qassim's supporters have been holding a permanent sit-in in Duraz for 11 months in front of the residence of Isa Qassim, who was sentenced to one-year suspended prison on May 21. He was also fined $256,000. 

The court confiscated his assets, including $9 million and two buildings. It found him guilty of illegally accumulating about $10 million for the purpose of provoking social unrest in the country.

The authorities had previously stripped Isa Qassim of his Bahraini nationality in June 2016 and then dissolved his political party, Al Wefaq.

Clashes between the police and protesters spread to other areas as well.

According to the Interior Ministry statement, security forces would remain deployed in the area where the sit-in camp was located, previously described as a "meeting ground for fugitives".

The majority of the Shia community in the country has made numerous protests in support of the cleric and against the Bahraini Sunni monarchy.