HONG KONG (Reuters) – Hong Kong’s metro operator opened all stations on Friday for the first time in a week ahead of another round of anti-government protests at the weekend, while the city’s legislature began its first session since protesters stormed the building in July.

Pro-establishment and democratic lawmakers shouted at each other before the start of the session, heightening tensions that have spiraled following four months of often violent pro-democracy protests in the Asian financial hub.

Some lawmakers wore black masks as they sat in the chamber, with others carrying placards reading: “Police brutality still exists, how can we have a meeting?”

The wearing of face masks was banned under colonial-era emergency powers invoked by embattled Hong Kong leader Carrie Lam a week ago.

The protests have plunged the city into its worst crisis since Hong Kong returned from British to Chinese rule in 1997 and also pose the biggest popular challenge to Chinese President Xi Jinping since he came to power in 2012.

The protests began in opposition to a now-withdrawn extradition bill but have since evolved into a pro-democracy movement fanned by fears that China is encroaching on Hong Kong’s freedoms guaranteed under the “one country, two systems” formula put in place with the 1997 handover.

China denies such claims and blames foreign countries, including Britain and the United States, for fomenting unrest.

Metro operator MTR Corp, whose network carries about 5 million passengers a day, said all lines would shut at 10 p.m. (1400 GMT) on Friday, more than 2 hours earlier than usual so more repairs could be carried out after protesters torched or trashed stations across the city.

Many stores and businesses have had to shut early due to metro closures, further hampering the city’s faltering economy as it faces its first recession in a decade.

Protesters have targeted the MTR because it has been blamed for closing stations on the government’s behalf to contain demonstrations.

The normally efficient system shut down completely last Friday following arson attacks and has operated only partially since then.

Lam introduced the emergency laws, including the ban on face masks, last Friday in an effort to quell unrest. However, the move sparked some of the worst violence since protests started.