Patrick Cockburn reports: Four men have been killed in protests this week by the Shia minority in eastern Saudi Arabia in the most serious outbreak of violence in the Kingdom since the start of the Arab Spring.

The Saudi Interior Ministry said yesterday that two of those who died had been shot in an exchange of fire between police and gunmen who had “infiltrated” the funeral of another protester killed earlier in the week.

The latest shootings show that protests by members of the two-million-strong Shia community, mostly concentrated in the oil-rich Eastern Province, are escalating. The Interior Ministry says that “a number of security checkpoints and vehicles have since Monday been increasingly coming under gunfire attacks in the Qatif region by assailants motivated by foreign orders”. It threatened harsh measures against anybody breaking the law.

Hamza al-Hassan, an opposition activist, said that the latest violence started last weekend when Nasser al-Mheishi, 19, was killed at a checkpoint near Qatif, an oasis which is a Shia centre. Mr Hassan says that “he was killed and left for three or four hours on the ground because the government refused to let his family collect the body”. This led to mass protests in and around the city of Qatif in which a second man, Ali al-Feifel, 24, was shot dead by police, doctors were quoted as saying by news agencies. The Saudi Interior Ministry could not be reached for comment on the allegations.