(Adds detail on relative size of consortium stakes, Cemex)
MEXICO CITY, Sept 9 (Reuters) - Mexican construction companies, including Grupo Ica and billionaire Carlos Slim's Grupo Carso, have formed a consortium to bid on contracts to build a new airport for Mexico City, construction industry group CMIC said on Tuesday.
The government last week unveiled plans for the $9.15 billion airport, which will eventually boast six runways.
British architect Norman Foster and Fernando Romero, Slim's son-in-law, won a contract to design the airport, which aims to reduce congestion and make Mexico City more competitive as a regional travel hub.
The nine builders, which also include Coconal, La Peninsular, Teya, Tradeco, Prodemex, Gia and Marhnos, have each taken stakes in a holding company and will take six-month-long turns heading the consortium, CMIC head Luis Zarate said.
The construction industry group's chief added that the team was most likely to win contracts to build runways and terminal buildings.
CMIC official Angel Macias said Mexican cement maker Cemex and steel company DeAcero were named as providers in a memorandum of understanding signed by members of the consortium.
That preliminary document showed that ICA had the biggest stake in the consortium at 18 percent, and Marhnos the smallest. Most of the companies had an 11 percent stake each, Macias said. (Reporting by Alexandra Alper; Editing by Jonathan Oatis)