PORT SAID, Egypt (Reuters) - Shipping through Egypt's Suez Canal was proceeding as normal on Saturday, an official from the canal authority said after violence flared in cities along its course in the past two days.

However, witnesses reported that operations at Port Said's port were halted when staff said they would suspend work due to the violence. Other factories and workplaces closed for the day.

Violence erupted on Friday and Saturday in Port Said, Ismailia and Suez, cities that run along the canal, a vital international trade route and major source of revenue for Egypt.

"Shipping movement through the Suez Canal is regular and is going ahead positively," canal spokesman Tarek Hassanein told Reuters, adding 44 ships had entered the canal so far on Saturday.

One witness reported that the army, which was deployed to Port Said, at the northern end of the canal, had sent troops to surround the branch office of the canal authority in the city.

The army had also been deployed in Suez at the southern end of the canal after violence on Friday there. The headquarters of the canal authority is in Ismailia, around the midway point.

At least 11 people were killed in Port Said on Saturday when violence erupted after a court sentenced to death 21 people accused of involvement in last year's Port Said soccer stadium disaster in which 74 people died.

(Reporting by Yusri Mohamed; Writing by Edmund Blair; Editing by Janet Lawrence)