BEIJING, Nov. 2  -- A couple who were filmed beating the man's mother in public have been expelled from the Communist Party of China (CPC), according to the local Party disciplinary authority in north China's Inner Mongolia Autonomous Region.

In September, a video showing a man and his wife beating the man's mother in public went viral online.

Dong Wenjiang, deputy secretary of the CPC disciplinary committee in Linxi County, confirmed the couple were public servants at the county market inspection bureau and social insurance bureau.

The brawl was sparked by a familial dispute over the education of the couple's son, Dong said.

The disciplinary committee launched an investigation into the incident and found the couple, Mr. Sun and Ms. Shang, violated Party rules.

According to a disciplinary rule of the CPC, a member shall be expelled from the CPC if his or her conduct violates morals and family virtues.

The committee stripped the couple of their CPC membership. Sun, the husband, was demoted from his post.

Party discipline is stricter than the law, and the expulsion shows the strict governance of the CPC, said Wu Hui, associate professor of the Party School of the Central Committee of the CPC.

CPC members need to ensure that they maintain their "advanced nature" and they should hold higher moral standards, said Wu.

How members handle family matters also falls under the oversight of the CPC disciplinary bodies, he added.

"Their conduct apparently had negative effects among the public and violated disciplinary regulations," Wu said.

Since the 18th CPC National Congress in 2012, CPC members have faced even more stringent rules, and members have been called upon to honor filial piety and family virtues, he added.