Ban Ki-moon, the UN secretary-general, called King Hamad of the Gulf state on Thursday to express his "deepest concern" about Bahrain''s use of force, which allegedly includes security forces preventing doctors from treating injured protesters, Aljazeera reported.

The secretary-general, who called during a visit to Guatemala, "expressed his deepest concern over reports of excessive and indiscriminate use of force by the security forces and police in Bahrain against unarmed civilians, including, allegedly, against medical personnel," a UN statement said.

He also "noted that such actions could be in breach of international humanitarian and human rights law"
Early on Friday, Bahrainis prepared to bury an activist killed on Wednesday, but it was not clear if large numbers of people would turn out for the funeral as they had for some of the seven killed in last month's crackdown.

The opposition vowed late Thursday to press on with "peaceful" demonstrations, undeterred by the military force deployed to quell their protests.

Five Shia activists and one Sunni dissident were arrested after the army imposed a curfew on parts of Manama using its powers under newly imposed martial law, opposition sources said.