Three employees of a private gas company in Chengdu, Sichuan province, were fined 500 yuan ($83) each on Monday, two hours after they rushed to open a digital hongbao - a red envelope containing money - issued by their boss on the company's WeChat social media group.

Other workers in the group did not open the red envelope until noon break. The boss, surnamed Luo, said he did it on purpose to check who didn't focus on work in the office.

On Dec 31, the company issued a rule banning mobile phone play in the office during working hours starting on Jan 1.