UPDATE 1-Abertis in talks to sell Luton Airport to AENA
* AENA teams up with AXA PE to buy Luton Airport - source
* Abertis' 90 percent of Luton worth 400 million euros (Adds AXA PE source on bid and background)
MADRID/PARIS, June 3 (Reuters) - Barcelona-based infrastructure firm Abertis is in talks with Spanish airport operator AENA to sell its stake in London Luton Airport, a spokesman said, in deal valued by the market at about 400 million euros ($521 million).
AENA, with a current 10 percent stake in Luton, is teaming up with AXA Private Equity of France to buy Abertis's 90 percent stake, a source familiar with the talks said on Monday.
Under the terms of its ownership pact with AENA, the Spanish airport holding has first refusal over Abertis' stake, put up for sale earlier this year as part of plan to focus on its toll road and telecommunications businesses.
Analysts have said AENA may want to expand its assets ahead of a government plan to privatise a minority stake in the holding company, but its heavy debt pile - 15 billion euros in 2011 - means that it needs a financial partner for such a bid.
AENA operates 50 Spanish airports, including Madrid's Barajas and Barcelona's El Prat, while AXA PE has assets of $32 billion managed or advised in Europe, North America and Asia, including a wide infrastructure portfolio.
Spokeswomen for AENA and AXA Private Equity declined to comment. ($1 = 0.7675 euros) (Reporting by Tracy Rucinski in Madrid and Christian Plumb in Paris; Editing by Lionel Laurent and Louise Heavens)