Media playback is unsupported on your device Media caption Chip Starnes has spoken to the media from the office where he is being held

Workers at a factory in Beijing have prevented their US boss from leaving for five days over a dispute.

Chip Starnes, co-owner of US company Speciality Medical Supplies, said dozens of workers "barricaded" him in over a dispute about severance pay.

However the workers said the dispute was over outstanding pay.

There have been numerous labour disputes in China's factories in recent years, where workers are not always fully protected.

Mr Starnes said workers had blocked all exits and, when he tried to sleep, were banging on doors and windows.

"I tried to leave a day and a half ago, and there was like 60 or 70 of them here inside every entrance, and every exit was barricaded," he told US broadcaster CNN.

Analysis The labor dispute at the Coral Springs Medical Supplies factory outside Beijing is getting a lot of attention because the boss holds an American passport. But whatever the wrongs and rights of this particular case, labour disputes over pay are an almost daily occurrence across China. When companies hit hard times, low-level workers are often the first ones to suffer. China's 260 million migrant workers are often treated as second-class citizens and it is difficult for them to use the weak legal system to their advantage. Without a reliable court system to turn to, desperate workers sometimes resort to extreme measures - some have tried to attract media attention by performing dance routines, or posting photos of their young children on weibo, China's version of Twitter. "I want to drink milk and eat cake. Hand over my parents' blood-and-sweat money," read a sign carried by one small boy in Yunnan province. In some cases, disgruntled employees resort to threats of suicide or violence. China's leaders have tried to increase the penalties for bosses who fail to pay their workers' salaries, but politically-connected factory owners often dodge substantial punishments.

The dispute began after the factory shut its plastics division, he said.

Around 30 workers who were laid off were given severance packages but other workers, who had moved to another division in the factory, also demanded severance packages, he said.

However workers at the factory said the dispute was over pay arrears, saying they had not been paid for two months.

A local union official, Chu Lixiang, told AP news agency that the workers feared the plant was closing and remaining workers would be left without severance payments.

Mr Starnes has disputed the workers' claims, telling CNN that "there are no outstanding balances". He said those workers asking for severance pay still had jobs.

Police were said to be at the scene and US embassy staff were also reported to have met Mr Starnes in the factory.

The police found no threat to Mr Starne's safety and believed it was a factory dispute rather than a criminal or kidnapping case, China Daily reported.

Zhao Lu, a spokesman of the Huairou Public Security Bureau, said he was unsure about the details of the labour dispute, but could "guarantee the personal safety of the manager".