BEIJING, Aug 26 (Reuters) - Microsoft Corp's sales of its media player and internet browser software in China have been "problematic," a Chinese antitrust regulator said on Tuesday, in response to questions about an ongoing anti-monopoly probe into the technology giant.

Zhang Mao, the head of the State Administration for Industry and Commerce, made the remarks at a media briefing in Beijing. He did not give details.

(Reporting by Koh Gui Qing and Paul Carsten; Editing by Ryan Woo)