As the Chinese government worked to regain control of the streets on Wednesday following ethnic clashes in the northwestern region of Xinjiang, Facebook reported some problems with its service, even as Beijing moved to suppress anger and dissent that is simmering online.

“We’ve heard reports of access issues and the service does appear to be running slowly. We’re looking into the matter,” a Facebook spokesman said via email, without elaborating.

On Tuesday, access to Facebook also seemed to be disrupted in some places, although the company maintained it was not seeing any changes in traffic. Still, users in Guangzhou, Shanghai, Beijing and Chongqing said they could not reach the site. In addition, access to Twitter was apparently blocked and search restrictions for Xinjiang topics were in place on Twitter’s Chinese rival, Fanfou.com.

Xinjiang is one of the most politically sensitive areas in China. Paramilitary police patrolled the streets in Urumqi, the region’s capital, on Wednesday to try to restore order after clashes between Muslim Uighurs and Han Chinee left 156 people dead and more than 1,000 injured.