* Qatar Airways to pay $661 mln for stake
* Joins concentrated register alongside Swire Pacific, Air China
* Qatar Airways also owns stakes in IAG, LATAM, Meridiana (Adds Air China comments, closing share price)
By Alexander Cornwell and Jamie Freed
DUBAI/SINGAPORE, Nov 6 (Reuters) - Qatar Airways has broadened its global reach by purchasing a 9.61 percent stake in Cathay Pacific, adding another strategic investor to the Hong Kong carrier's complicated share register at a time when it is looking to cut costs.
Hong Kong's Kingboard Chemical Holdings said it had sold the stake to Qatar Airways for HK$5.16 billion ($661 million), making the Middle Eastern carrier the third-largest shareholder in Cathay.
For Cathay, the Qatar stake will give it a third strategic shareholder behind Swire Pacific Ltd and Air China Ltd , potentially complicating a restructuring plan aimed at slashing HK$4 billion in costs over three years.
Without domestic flights to underpin earnings, Asian carriers Cathay and Singapore Airlines Ltd have struggled against Chinese and Middle Eastern rivals, with Cathay already shedding 600 jobs since May.
For state-owned Qatar Airways, its first major stake in an Asian airline will allow it to boost its global influence and potentially increase traffic through its Doha hub, amid the worst political crisis in years among the Gulf Arab states.
The airline has been unable to fly to the previously lucrative markets of the United Arab Emirates and Saudi Arabia as part of an airspace rights dispute with neighbours, and has been looking to invest elsewhere to broaden its reach.
It was rebuffed by American Airlines Group Inc earlier this year.
Despite Cathay's troubles, Qatar Airways Chief Executive Akbar al-Baker described it as "one of the strongest airlines in the world ... with massive potential for the future".
Cathay shares have risen by 29.4 percent since the start of January despite the airline in August posting its worst first-half loss in 20 years.
Shares of Cathay Pacific dropped as much as 4.7 percent on Monday morning, as investors worried about its direction with Qatar Airways on its registry. The stock closed 1.5 percent lower, while the broader market was flat.
"Cathay will have three major shareholders, all with different and potentially conflicting interests - Swire, Air China and Qatar Airways," said Corrine Png, CEO of transport research firm Crucial Perspective.
"This may not necessarily be favourable for Cathay as it is facing operating challenges and undergoing transformation."
Swire Pacific owns 45 percent of Cathay and Air China 30 percent. Air China said on Monday that it viewed Qatar Airways' purchase of the Cathay stake "positively" and that it hoped the shareholders could work together to find synergies.
Will Horton, a Hong Kong-based senior analyst at CAPA Centre for Aviation, said that while Qatar Airways' investment in Cathay was likely to be passive, difficulties could arise if they tried to better integrate their hubs.
Cathay flew between Hong Kong and Qatar Airway's Doha hub as part of a codeshare arrangement between 2014 and 2016, when the route was axed "for commercial reasons".
Qatar Airways' investment strategy has seen it acquire 20 percent of British Airways-parent International Consolidated Airlines Group, 10 percent of South America's LATAM Airlines Group SA and 49 percent of Italy's Meridiana.
Investment holding company Kingboard said it would recognise a gain of HK$800 million on the sale of its entire Cathay stake. ($1 = 7.8021 Hong Kong dollars) (Reporting by Alexander Cornwell and Jamie Freed, additional reporting by Brenda Goh in Shanghai; Editing by Stephen Coates and Himani Sarkar)