* Li Ka-shing to retire after annual general meeting on May 10
* Li will stay on as senior adviser to the group
* Son Victor Li will take over the reins of the business (Adds quotes, comment)
HONG KONG, March 16 (Reuters) - Hong Kong's richest man, Li Ka-shing, announced his retirement as chairman of CK Hutchison Holdings Ltd on Friday, bringing to a close a rags-to-riches story that made him a hero in the freewheeling capitalist hub.
Li, 89, will retire after the annual general meeting on May 10, the ports-to-telecoms conglomerate said in a filing to the Hong Kong bourse. A factory apprentice when he was 13, Li, was called "Superman" for his work ethic and business success.
While Hong Kong's adoration of the billionaire and his story has waned somewhat in recent years, he is still stepping aside from one of Asia's most outward-looking empires, spanning more than 50 countries and 323,000 employees at last count.
"I've been working for a long time, too long," a relaxed Li told reporters.
Li will, as expected, stay on as senior adviser. His eldest son Victor Li, who was named successor several years ago, will take over the reins of the business. Victor, already on the board, is seen as a steady hand unlikely to change course.
"I've always said I could go on a trip anytime, the company would still run the same way," Li said.
During his tenure, Li had increased the pace of overseas acquisitions, helping boost the group's profits with growth in the European telecoms business offsetting a drop in the value of the British business following Brexit.
Through his flagship CK Hutchison, Li controls the biggest container port operator in the world, Canadian oil giant Husky Energy Inc, one of Europe's leading telecoms operators, as well as infrastructure assets and a long-time interest in Britain that saw him awarded a knighthood in 2000.
"Li Ka-shing is remarkable - he's a role model and I regard him as such," said Stuart Gulliver, former CEO of HSBC who in a 38-year career with the bank worked closely with Li.
It was HSBC's 1979 sale to Li of a stake in Hutchison Whampoa, a colonial-era trading house, that vaulted him into the first rank of Chinese tycoons.
Commending Li's long laid-out succession plan, unusual among tycoons in a region where discussing death is often viewed as unlucky, Gulliver praised Victor for being extremely capable.
"He's also been very actively involved - he has been running it day to day and he has been for some time," Gulliver said.
STRONG RESULTS AT LI'S COMPANIES
The news of retirement came together with the announcement of better-than-expected results at some of Li's biggest firms.
CK Hutchison reported a 6 percent rise in 2017 profit to HK$35.1 billion ($4.48 billion), versus the average forecast of HK$34.63 billion from 12 analysts polled by Thomson Reuters.
The real estate arm CK Asset Holdings Limited saw annual profits surge 55 percent, also beating estimates.
"Healthy and synchronised growth in major economies gathered pace in 2017. Provided this trend continues and inflation remains benign, the environment in 2018 should remain supportive for global trade and for our businesses," Li said.
Li, who ranked 23rd on the world's rich list by Forbes, is the wealthiest tycoon in Hong Kong, a former British colony that returned to China in 1997.
Over the past few years, Li's close ties with Beijing's Communist Party leadership have come under scrutiny. He has never been publicly over-critical.
"I like to read history very much... and about my country. If I can vote today, on the constitutional reform (in China) so (President) Xi (Jinping) can go for another term ... I will vote for him," Li said.
"My relationship with the central government is pretty good. But personally I don't say things that I shouldn't say."
There was a media report last year indicating Li would retire in 2018, but the billionaire businessman had brushed it off, saying he had not yet decided when to step down and that he would stay on as an adviser even after retirement.
CK Hutchison shares closed up 0.3 percent on Friday, versus a 0.1 percent fall in the benchmark Hang Seng index. ($1 = 7.8432 Hong Kong dollars)
(Additional reporting by Jennifer Hughes and Carmel Yang, Writing by James Pomfret; Editing by Nick Macfie and Himani Sarkar)