Quanjude Group, a famous chain of Peking duck restaurants, on Monday issued an apology after it was discovered waste oil from its kitchens was being recycled and resold to street vendors in Beijing.

"We attach great importance to the responsible disposal of waste oil," the company said in a statement posted on its website. "We sincerely apologize and we accept the public and media criticism."

The statement followed the arrest of Wang Duohao by Beijing authorities.

The 40-year-old, who collected oil from Quanjude restaurants in the capital's Sanyuanqiao and Aoyuncun neighborhoods, is accused of supplying "gutter oil"?- recycled waste oil?- to street vendors and other people from 2004 to October 2011.

He has been charged with supplying "poisonous or harmful food", which carries a maximum penalty of death if it is proved to cause death or serious injury.

Quanjude earlier denied its staff had any knowledge that Wang was reselling waste for its kitchens.

However, on Monday the company admitted it had not regulated the process adequately.

"We will continue to fulfill our social responsibility and will strengthen our waste management regulations," the statement said. "We welcome supervision by the public and the media."

The company said it has cooperated fully with the police investigation into Wang.

The two restaurants involved have already changed to another recycling company, according to the statement.