HONG KONG, June 23 (Reuters) - Hong Kong's benchmark index had its worst day in more than three months on Monday, with a small morning gain on a good flash China PMI number wiped out by across-the-board tumbles in the afternoon that seemed to catch analysts off guard.
The Hang Seng Index closed down 1.7 percent at 22,804.81 points, its biggest daily percentage loss since March 20.
The China Enterprises Index of the leading offshore Chinese listings in Hong Kong slid 1.9 percent, its worst day since April 15.
Traders seemed at a loss to explain the slide. Some said it was triggered by profit-taking by investors worried about a near-term correction on the index, which had held above the 23,000-level for two weeks.
Index futures-related trading was another factor, according to analysts.
Nearly all Hang Seng components fell. Property developers were some of the heaviest hit, with Sino Land down 3.9 percent and New World Development off 2.5 percent.
China's big four banks were all weaker. Bank of China sank 2.6 percent to its lowest level since May 7, a big drag on the H-share index.
Great Wall Motor shed 4.5 percent after mainland media reported changes in several management posts during the weekend. (Reporting by Grace Li; Editing by Richard Borsuk)