A US consulate in China has suspended some of its operations, an official said Tuesday, after receiving an envelope which contained an "unidentified substance", reportedly white powder.

The consulate in the southern city of Guangzhou "received an envelope which contained an unidentified substance," on Monday, deputy US embassy spokesman Justin Higgins told AFP, adding that no one had been injured.

"We have not yet identified the substance," he said, adding that one part of the consulate had "temporarily suspended operations".

The Yangcheng Evening News, a Guangzhou paper, said the envelope contained a white powder. The consulate is mainly responsible for processing visas for Chinese citizens, it added.

US officials processed more than 1.34 million non-immigrant visa applications from Chinese citizens in 2012, up 34 percent from 2011, the embassy says on its website.