By Asma Alsharif

CAIRO, Sept 12 (Reuters) - An Egyptian court on Thursday acquitted all 14 defendants, including policemen, accused of killing 17 protesters during the bloodiest day of a revolt that toppled autocrat Hosni Mubarak over two years ago, judicial sources said.

The deaths in Suez City triggered violence across Egypt on what was later called "The Friday of Rage" - Jan. 28, 2011 - that fuelled an 18-day uprising against Mubarak, who had ruled Egypt for 30 years.

The verdict could add to tensions in Egypt, which has been gripped by a political crisis since the army overthrew President Mohamed Mursi of the Muslim Brotherhood on July 3 after mass protests against his rule.

The Brotherhood and some human rights activists accuse the army-backed government of trying to bring back the old order, accusations it denies.

The government accuses the Muslim Brotherhood of inciting violence and carrying out terrorist acts, charges that it in turn it denies. Many of its leaders have been arrested.

LIGHT SENTENCES

The case is the latest in a series in which Mubarak-era officials were either acquitted or given light sentences, raising frustrations among opponents of the government and the old regime.

A total of around 850 protesters were killed across the country during the 2011 revolution in the Arab world's most populous country.

The 14 defendants in the Suez case - 10 police officers, a businessman and his three sons - were arrested in 2011 and accused of firing rounds and birdshot at peaceful protesters.

"The Suez criminal court has acquitted all the defendants of charges of killing and attempting to kill demonstrators during the events of the Jan. 25 revolution," a judicial source said.

The judge did not provide reasons behind the verdict.

Police cleared the court room after families of victims broke down and screamed. Some fainted after hearing the verdict, a witness who attended the court session said.

"Today the blood of Egyptians has become cheap. The rulings that come out in Egypt are politicised," said Ali Gunaidi, the spokesman for the Suez victims' families.

"There are no rulings in accordance with the laws but rather they are according to orders."

(Editing by Michael Georgy and Ralph Boulton)