Chinese mainland stocks listed in Hong Kong rallied the most in three weeks after a private manufacturing index unexpectedly jumped to the highest level since February last year.

The Hang Seng China Enterprises Index closed up 1.9 percent, its biggest advance since July 11, with China Longyuan Power Group Corp and a pair of automakers leading gains. Shares traded on the mainland extended last week's decline, with the ChiNext index of smaller companies retreating 1.1 percent on continuing concern over the impact of plans to crack down on wealth-management products.

A factory gauge from Caixin Media and Markit Economics jumped to 50.6 in July from 48.6 a month earlier, data showed on Monday, while an official measure dropped to 49.9. The ChiNext measure retreated last week amid reports regulators are planning to limit WMP investments in equities.