BEIJING (AP) — Hundreds of Chinese factory workers angry about new work rules held their Japanese and Chinese managers hostage for a day and a half.

A statement from the Japanese parent company says the protest at Shanghai Shinmei Electric Company started Friday morning and ended Saturday night. Shinmei Electric says 10 Japanese nationals and eight Chinese managers were held against their will at the Shanghai factory and they were released uninjured after 300 police officers were called to the factory.

A security guard at the Shanghai plant said Tuesday that workers were protesting new work rules. He says they include workers only having two minutes to go on a bathroom break and being fined 50 yuan ($8) if they are late once and fired if late twice.