* Heineken first Champions League sponsor for 2015-2018
* Champions League cumulative audience 4.2 bln people
* About half of audience outside Europe
* Estimated sponsorship cost was 50-55 mln euros per year
* Question marks over rugby's Heineken Cup (Adds estimate on sponsorship cost)
By Philip Blenkinsop
BRUSSELS, Oct 30 (Reuters) - Heineken, the world's third largest brewer, has extended its sponsorship of the Champions League, Europe's premier club soccer competition, for three years.
The Dutch beer maker, whose flagship Heineken brand has been a sponsor since 2005, and European soccer's governing body UEFA told Reuters on Wednesday that they had agreed a deal covering the period from 2015 to 2018.
Heineken, previously a partner with UEFA through its Amstel brand, is the first Champions League sponsor to renew beyond the current 2012-2015 term, although German sports goods maker Adidas has extended as an official supplier.
Other current sponsors are Ford, Gazprom, MasterCard, Sony's PlayStation and UniCredit , with HTC as another supplier. There are reports that UEFA might look to add an airline as a seventh sponsor.
Both parties declined to disclose financial details.
Sports Sponsorship Insider, part of sports marketing research group SportBusiness, estimates the current partnership costs Heineken 50-55 million euros ($68.9-75.7 million) a year.
"That was a 15 percent increase on the previous cycle. I think another 15 percent would be the benchmark UEFA would be trying to hit," said Insider editor Matthew Glendinning.
Heineken is the leading brand in the higher margin international premium segment of the global beer market, brewing 2.9 billion litres last year for consumption outside the Netherlands.
"As Heineken is available in 220 countries in the world and so is the UEFA Champions League, this platform really is to build the Heineken brand worldwide," said Heineken's global activation manager, Hans Erik Tuijt.
Unlike rivals, such as Carlsberg, Heineken does not sponsor teams or individuals.
The Champions League is the most watched annual sporting event. The total audience is estimated at 4.2 billion, with more than 1 billion people watching around four matches per season and half of that audience outside Europe.
"The number of Brazilian players playing in the Champions League is significant, and of Argentinian players is significant, and Asians love to watch this great football," said UEFA marketing director Guy-Laurent Epstein.
The new deal will increase the time Heineken is shown on LED boards around the ground to 13 minutes from a previous nine. The boards will also be used in the future in group phase matches.
Heineken will also have quicker access to images, enhancing its social media such as a live Twitter feed linked to matches.
It will retain the right to take the trophy to soccer fans, with Buenos Aires, Lagos and Ho Chi Minh City - major Heineken markets - on its schedule early next year.
Heineken is the largest seller of beer in Europe, but is also number two in Africa and has boosted its presence in higher growth emerging markets, with expansion into Mexico in 2010 and in Asia last year.
Heineken spent some 2.25 billion euros last year on marketing, 12 percent of its revenue.
That extends to rugby, in sponsoring rugby's World Cup and, at least until the end of this season, the premier European club competition, the Heineken Cup, which is under threat from a possible breakaway by English and French sides.
"I hope they are growing pains, as I really believe the competition is fantastic ... I hope the clubs, unions and the rugby officials will come to a sensible solution so that it becomes an even better competition," Tuijt said.
"We need to know what the outcome is because the English clubs are focal." ($1 = 0.7262 euros) (Editing by Stephen Wood and Toby Davis)