Syrian forces kill 10 protesters in Aleppo-activists

(Adds video footage, details)

AMMAN, June 22 (Reuters) - Syrian troops killed at least 10 people in the main commercial hub of Aleppo on Friday when they opened fire on a crowd of demonstrators with heavy machine-guns, opposition activists said.

Thousands of demonstrators denouncing President Bashar al-Assad were marching toward the city's central Saadallah al-Jabiri Square when four armoured vehicles opened fire, activists told Reuters by phone, including two who said they were speaking from Aleppo.

"The wounded were taken to houses and are trapped there. They cannot be transported to hospitals because troops and Shabbiha (pro-Assad militia) are surrounding the neighbourhood," Mohannad, one of the activists, said by phone.

He was referring to the middle class district of Saladin, where the demonstration broke out.

Activist video footage posted on the Internet show a large crowd of protesters, some draped in the revolutionary flag, running along a street as heavy gunfire could be heard. Another video showed a man, whose chest was covered in blood, being dragged along the road.

Aleppo, a conservative Sunni Muslim city of 3 million people, has been slowly joining the protest movement against Assad as alliances between the city's merchant class and the ruling elite, from Assad's minority Alawite sect, have started to collapse in recent weeks.

The city's merchants have been staging intermittent strikes to protest shelling and aerial bombardments on towns and villages surrounding Aleppo, and demonstrations demanding Assad's removal have become a regular occurrence in the city.

Live video footage broadcast by activists showed large crowds taking to the streets in anti-Assad protests across Aleppo on Friday. (Reporting by Khaled Yacoub Oweis Amman newsroom and Ayat Basma in Beirut)