UPDATE 1-Investor group considers listing Aeromexico abroad

(Recasts, adds detail on expiration date)

MEXICO CITY, Oct 15 (Reuters) - Citigroup (C.N: Quote, Profile, Research, Stock Buzz) and its Mexican investment partners said on Monday they plan to float at least 15 percent of Aeromexico on local and international markets if their offer to buy the troubled airline succeeds.

The investor group sweetened its offer for Aeromexico AMEXICOA.MX last week by offering warrants on top of its original $160 million bid. The group is also promising a $240 million investment injection into the loss-making airline.

Mexico's government owns 62 percent of Aeromexico and its holding company, Consorcio Aeromexico, while the rest of the company is listed on the Mexican stock exchange.

If the offer is accepted, the new management would delist the carrier and later relaunch it in a share offering.

"We would list (stock) in the Mexican market, and potentially on international markets, through a public offering of at least 15 percent of Consorcio Aeromexico or its main subsidiary," said Jose Luis Barraza, who represents the investor group.

The group forecast that Aeromexico could become profitable in 12 to 16 months after the buyout.

Aeromexico posted a loss of 679 million pesos, or $63 million in the second quarter. It has been hurt by competition from domestic discount rivals and foreign carriers.

Banamex, Citigroup's Mexican unit, said the expiry of the public offer was being extended one day, to Oct. 17.