HONG Kong's benchmark stock index rose the most in three weeks as concern eased that China Mobile Ltd's earnings would be hurt by mergers among smaller rivals.

China Mobile, the world's largest phone company by users, climbed the most since May 13, accounting for one-quarter of the benchmark's advance. CLP Holdings Ltd, Hong Kong's biggest power utility, tumbled by the most in a decade after posting its biggest gain in eight years on May 30.

The Hang Seng Index climbed 298.24, or 1.2 percent, to close at 24,831.36, the biggest gain since May 13. The Hang Seng China Enterprises Index, which tracks so-called H shares of Chinese companies, added 1.9 percent to 14,026.37, said Bloomberg News.

China Mobile jumped HK$2.90 (37 US cents), or 2.5 percent, to HK$117.60, the biggest gain since May 13. It's down 15 percent this year. China Unicom Ltd, the nation's second-biggest mobile-phone company, and China Netcom Group Corp were due to jointly announce details of a merger and the sale of some assets.

"People are feeling that the downside for China Mobile is not as bad as previously thought," said Andrew Sullivan, a sales trader at Mainfirst Securities Hong Kong Ltd. "Now that there will be an announcement, people are turning more positive."

The deals are part of the government's proposed reorganization of the telecommunications industry announced on May 24.