Police officers carry barriers outside Hong Kong government offices as they prepare for a protest by democracy activists in Hong Kong on August 31, 2014. The top committee of China's legislature is expected to announce its decision on political reform for the southern city on August 31. Alex Ogle/AFP/Getty Images

China's legislature has ruled against allowing open nominations for the election of Hong Kong's chief executive. The standing committee of China's National People's Congress ruled candidates must be approved by more than half a nominating committee.

"Since the long-term prosperity and stability of Hong Kong and the sovereignty, security and development interests of the country are at stake, there is a need to proceed in a prudent and steady manner," the Standing Committee said in their decision.

The decision is expected to mean that only candidates who support the Beijing government will be able to contest the elections for Chief Executive -- the highest post in the Special Administrative Region's devolved government. Critics complain the nominating committee is beholden to Chinese leaders.

The ruling is likely to trigger protests from pro-democracy activists. Occupy Central, an activist movement in the city, has pledged to occupy the city's main business district if restrictions are put on democracy. The group announced plans to rally Sunday evening, and authorities have reportedly detailed 7,000 police officers to monitor the assembly.

Hong Kong has enjoyed a comparatively high degree of political autonomy since it was returned to Chinese rule by the U.K. in 1997. China has, however, become increasingly concerned at the prospect a non-Beijing approved chief executive could be influenced by foreign powers.

Earlier this month, Chinese officials told pro-Democracy politicians in Hong Kong it was a requirement for the city's next leader to be a “staunch patriot,” a phrase many interpreted as being approved by the Communist Party government.