By Abdel Rahman Youssef

ALEXANDRIA, March 3 (Reuters) - Two Egyptian policemen were sentenced to 10 years in prison on Monday for torturing an activist to death in 2010 in an incident that became one of the triggers for the uprising that toppled veteran autocrat Hosni Mubarak.

Witnesses and rights groups said that 28-year-old Khaled Said died after police dragged him out of an Internet cafe in the Mediterranean city of Alexandria and beat him to death.

Before he died, Said posted an Internet video purportedly showing two policemen sharing the spoils of a drug bust.

His death galvanised anger, in particular through the Facebook page "We are all Khaled Said" that focused attention on the rights violations by the police that many said were commonplace at the time.

That campaign, tapping into a tech-savvy but disillusioned youth, plus a myriad other strikes, groupings and protests, morphed into nationwide marches calling for the dissolution of parliament and disbanding of the state security agency.

Government autopsies carried out before the 2011 uprising found that Said had choked on a plastic roll of drugs and his injuries were not the cause of his death.

The two policemen were sentenced to seven years in prison in 2011, but a court cancelled the ruling after an appeal and ordered a retrial. On Monday, they were sentenced to 10 years.

"We wanted the death penalty... 10 years is too little," Said's sister Zahra told Reuters.

"Still this is a victory for the January 25 revolution because the symbol that they tried to tarnish turned out to be innocent," she added referring to the revolt against Mubarak.

Under Mubarak, human rights groups accused the police of widespread torture.

Activists say security forces are again abusing power since the army ousted President Mohamed Mursi of the Muslim Brotherhood last July following mass protests against him.

Authorities deny the accusations and say they are committed to democracy as Egypt moves towards presidential and parliamentary elections expected in a few months.

While much of the population lionises the police now, Islamist militants based in the Sinai Peninsula near Israel have stepped up attacks on police and soldiers since army chief Field Marshal Abdel Fattah al-Sisi deposed Mursi. Hundreds have been killed.

In the southern city of Beni Suef, a policeman was shot dead by gunmen on Monday. Two other policemen were wounded in separate shooting attacks in Giza near Cairo and Daqahliyah province in the Nile Delta, state media reported.

Egyptian authorities have mounted a crackdown against the now banned Brotherhood, killing about 1,000 on the streets and arresting thousands of others.

Security forces have extended the campaign to include secular activists, including ones who supported Mursi's downfall and played important roles in the toppling of Mubarak. (Writing by Shadia Nasralla and Asma Alsharif; Editing by Michael Georgy and Alison Williams)