File photo of Sun Yang. [Photo/Xinhua]

Two-time Olympic swimming champion Sun Yang was released on Monday morning after being detained for seven days for driving without a license.

The China News Service quoted unidentified sources of a detention house in Hangzhou, Zhejiang province, as saying that the 22-year-old left at about 8:30 am on Monday, without exiting from the regular passageway used by other detainees.

The London Olympic 400m and 1,500m freestyle winner was arrested for driving without a license after a minor traffic accident in Hangzhou on Nov 3.

He received further punishment as the Chinese Swimming Administrative Center announced last week that he was suspended from competitions and training.