(Updates with Caisse CEO comments)
By Alexandra Alper
MEXICO CITY, Aug 14 (Reuters) - Mexico's top builder, ICA , is planning to bid for a contract to build three runways for a new $13 billion airport for Mexico City, two sources familiar with the situation told Reuters.
The new airport project is aimed at eventually turning Mexico City into a major regional air hub with six runways serving up to 120 million passengers a year.
ICA Chief Executive Officer Alonso Quintana was not immediately available for comment.
One of the sources said that ICA would "most likely" bid alone for the runway construction job, but added that the company was seeking consortium partners for other airport-related tenders.
Tenders for project infrastructure are on track to start in September, after Mexico said last month it was seeking some $6 billion in bids from contractors to build the airport.
Last September, Mexico's government unveiled the winning design by British architect Norman Foster for a futuristic airport nestled in the northeastern part of the capital that will ease delays and boost traffic.
A source told Reuters earlier this week that 70 percent of the project could be funded by private investors, up from an original estimate of just 42 percent, as weak oil production has hit Mexico's public finances.
ICA's shares have fallen nearly 20 percent this week as Mexico's tumbling peso has fanned investor concerns about the company's sizable dollar-denominated debt burden.
But CEO Quintana told Reuters earlier on Friday that the company was not seeking a capital injection or planning to sell more of its stake in airport operator OMA.
Michael Sabia, chief executive of Canada's second-largest pension fund manager, Caisse de depot et placement du Quebec, said he was confident in ICA.
"With respect to our partner ICA, we continue to think they are a very high quality operator, that they are a high quality partner for us," Sabia told reporters on Friday on a conference call in Montreal. "They have a substantial presence in the infrastructure business in Mexico, so we're very comfortable continuing to work with them."
Sabia said Caisse would continue to look for opportunities in real estate, infrastructure and private equity in Mexico. (With reporting by Cyntia Barrera in Mexico City and Allison Lampert in Montreal; Editing by Lisa Shumaker)