(Adds details on debt, analyst quote, expected Slim family position in Telesites)
MEXICO CITY, April 1 (Reuters) - Mexico's America Movil, the telecoms company controlled by billionaire Carlos Slim, said on Wednesday it would propose spinning off its local cellphone tower business into a separate, listed company known as Telesites.
Last year Slim said he wanted to sell assets to try and shrug off the burden of new regulations designed to curb his dominance of the local phone and data markets.
America Movil said that under the plan, current shareholders would receive the same number and series of Telesites shares as they held in America Movil at the moment that the new, independent company is hived off.
The proposal, which foresees transferring some 21 billion pesos ($1.39 billion) of America Movil debt onto Telesites, must be approved by shareholders at a meeting on April 17. At the end of 2014, America Movil reported total debt of $41.2 billion.
Subject to regulatory approval, Telesites shares would be listed and traded on the Mexican stock exchange without there being a public offering of the stock, America Movil said.
Shares in America Movil closed up 3.58 percent at 16.22 pesos before main details of the plan were announced.
Homero Ruiz, telecoms analyst at Signum Research, said the announcement should allay market uncertainty about the spin-off.
"The (America Movil) share price is likely to be negatively affected, but I don't think it will be that much," he said.
Slim's flagship company, which is facing tough new anti-trust regulation in Mexico, said it believed the spin-off would allow its competitors to have access to about 90 percent of its towers, up from around 45 percent at the moment.
America Movil said in February the planned spin-off of cellphone towers in Mexico was at an advanced stage and should be up and running by May or June of this year.
Gabriel Contreras, the head of Mexico's telecoms regulator, said last week the watchdog will not necessarily impose tougher rules against America Movil if it does not go ahead with its plan to sell off assets.
Contreras added, though, that as long as it is controlled by the same shareholders, it will face dominance regulation.
America Movil said that in the first two years after the spin-off, the Slim family could maintain a majority position in Telesites, which will focus on building, installing, maintaining, operating and commercializing different types of towers and supporting structures.
$1 = 15.1355 pesos Reporting by Veronica Sparrowe, Michael O'Boyle, Joanna Zuckerman Bernstein, Gabriel Stargardter, Jean Luis Arce and Elinor Comlay; Editing by Dave Graham, Bernadette Baum and Lisa Shumaker