FEATURE-Egypt's army draws fire over military trials

* 10,000 civilians given military trials since Mubarak quit

* Army says trials are only for serious crimes

* Trials weaken judiciary, threaten transition - activists

By Dina Zayed

CAIRO, July 21 (Reuters) - Actor Aly Sobhy's trial in an Egyptian military court lasted just 20 minutes, hours after he was detained in March with more than 160 other protesters in central Cairo.

He was among a score of lucky ones acquitted of charges of "thuggery" after a campaign for their release. But he spent four days in custody and now questions the army's intentions.

"There are thousands of youth held in military prisons simply for the reason that they were on the street at the wrong time. It's a plan to dismantle the revolution. If they arrest some, others will be scared to go protest," he told Reuters.

Anger at the army's handling of the transition to civilian rule is growing. Demonstrators camped out in Cairo's Tahrir Square say the army is taking too long to purge the system and end the corrupt practices of the Hosni Mubarak era.

Protesters cite the widespread use of military courts to try civilians, a common practice under the ousted president and since adopted by the army council led by Field Marshal Mohamed Hussein Tantawi, Mubarak's defence minister for two decades.