Human Rights Watch accused Egypt's military on Saturday of beating and torturing protesters arrested during clashes with soldiers in Cairo earlier this month.

The New York-based group said soldiers "beat and tortured" protesters arrested in the May 4 clashes outside the defence ministry and arrested at least 350 demonstrators.

"The brutal beating of both men and women protesters shows that military officers have no sense of limits on what they can do," Joe Stork, its deputy Middle East and North Africa director, said in the statement.

HRW based its statement on testimony from released protesters and video footage that captured soldiers beating those they arrested.

The military has come under criticism before for brutally beating protesters in Cairo's Tahrir Square last December and conducting virginity tests on detained women activists.

The protest outside the defence ministry began as a sit-in by supporters of a populist Islamist barred from running in next week's presidential election.

But it was joined by secular-leaning activists who believe the military, in charge since an uprising ousted president Hosni Mubarak last year, intends to exercise power even after the election, which should mark the end of military rule.

The military says one if its commandos was killed in the May 4 clashes, which pitted rock-throwing protesters against baton-wielding soldiers backed by armoured personnel carriers.

The clashes came two days after up to 11 people died when men in plainclothes attacked the sit-in, stirring a backlash against the military for not protecting the protesters.