Armed fighters driving vehicles mounted with machine guns opened fire on a police checkpoint in Egypt's Sinai peninsula, killing two policemen and injuring a third in a daring attack, security officials have said.

Officials, speaking on the condition of anonymity, said on Sunday that policemen opened fire at the attackers, but had failed to stop the gunmen from fleeing the site, south of the airport in the city of al Arish.

Fighters have stepped up their activity in Sinai since last year's uprising, taking advantage of a security vacuum after many members of the hated police force disappeared from the streets.

The lawlessness in the Sinai has been complicated by sour relations between the local Bedouin tribes and the security agencies, who were accused of mistreating them under the old regime of Hosni Mubarak.

In a separate development, an Egyptian judge referred a police officer to trial after a mobile phone video posted on the Internet purportedly showed him shooting at the eyes of protesters during clashes in November.

Officer Mahmoud Shennawy, dubbed the 'eye sniper'' by protesters, is charged with attempted murder of five protesters.

The shootings took place during intense clashes between protesters and security officials around Tahrir Square that left more than 40 dead.

Source: Agencies