Hundreds of Egyptians protested in Cairo and other cities on Friday over the death of an activist, whose case has raised concerns among Western governments and has spurred demonstrations at home calling for political change.

Khaled Said, 28, died on June 6 in Alexandria. Witnesses and rights groups say two policemen dragged him out of an Internet cafe and beat him to death. Official autopsies said he choked on a plastic roll of drugs, but two officers will stand trial.

The demonstration was organized by a Facebook group called We Are All Khaled Said.

The extent to which web groups can turn online support into street protests is being watched closely before a parliamentary election this year and a presidential poll the year after.

President Hosni Mubarak, 82 who has been in power since 1981, has not said if he will run in 2011. If he does not, many believe he will seek to push his son, Gamal, 46, into office.

Other online groups calling for change have also emerged, including ones backing Mohamed ElBaradei, the former head of the U.N. nuclear watchdog who has said he might run for president.

The Said protest group, which has about 180,000 online backers, told its followers to wear black T-shirts and stand silently at specified places.

A group in Cairo, barred from a site it intended to use, regrouped outside the journalists' syndicate.

Officer, how can you sleep at night when you are torturing the people, they chanted.

Smaller numbers elsewhere in Cairo stood at intervals along streets in silence, some reading the Koran. The Facebook group told protesters not to stay in groups in order to circumvent an emergency law that can restrict even small gatherings.

If many people stand and protest, surely there will be an end to torture, said Fatima Mohamed, 24, who turned up after learning about the protest plan on Facebook.

A few hundred stretched along the seaside boulevard in Alexandria, some holding black flags with Said's image, a witness said. Dozens protested in Damietta and Tanta, other witnesses in these cities said.

Extra police were at planned protest sites. Egypt's police are usually swift to contain protests and often heavy handed, tending to limit protest numbers to no more than a few hundred.

The death of Said, who posted an Internet video purportedly showing two policemen sharing the spoils of a drug bust before he died, raised concerns among Egypt's U.S. and European allies.

Analysts say such groups have yet to show they can rally mass protests in a country of 78 million to force change on a government that has huge security forces at hand. But protests are drawing unwelcome international attention, they have said.

(Additional reporting by Reuters Television, writing by Edmund Blair; editing by Michael Roddy)