|Beijing: BBC News|
Chinese police are investigating claims that a security firm colluded with officials to detain protesters in secret prisons, known as "black jails".
State media said police had arrested the chairman and general manager of the company, Anyuanding Security Services.
It is alleged they took money from local governments to abduct and imprison people who travelled to the capital, Beijing, to complain about local injustices.
The company denies this.
Human rights groups say China has hundreds of such jails, and detainees are often subject to abuse - but the Chinese government has repeatedly denied they exist.
Anyuanding chairman Zhang Jun, and general manager Zhang Jie, were detained for "illegally detaining people and illegal business operations", reported the official China Daily, quoting other media outlets.
It did not say when the detentions took place.
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