SAO PAULO, Dec 14 (Reuters) - TIM Participacoes, Telefonica Brasil SA and America Movil SAB de CV's Claro won an auction on Monday to acquire the mobile operations of Brazil's Oi SA with a joint bid of 16.5 billion reais ($3.23 billion), the companies said in a series of securities filings.

The winning trio, which had submitted an initial bid in July, plans to split Oi's assets once they have antitrust approval. Oi, which filed for bankruptcy protection in 2016, is selling assets to repay creditors.

The group was the auction's sole bidder, according to the filings.

The companies said the base price came to 15.744 billion reais, with another 756 million reais to finance so-called "transition services," which Oi will carry out over the next year in order to facilitate the transfer of assets.

TIM Participacoes, the local unit of Telecom Italia SpA , will pay roughly 7.3 billion reais of the base price and another 476 million reais for the transition services, it said in a filing.

Telefonica Brasil, the local unit of Spain's Telefonica SA , will pay roughly 5.5 billion reais of the base price and 179 million reais in transition services, it said in a separate filing.

Claro will pay 22% of the total 16.5 billion reais, and in exchange be granted 32% of the subscriber base from Oi's mobile business, it said in its own filing.

In their new bid, TIM, Telefonica Brasil and Claro also offered Oi a long-term contract to rent its telecom infrastructure.

Reuters reported on the overall pricing of the bid earlier on Monday.

Brazil-listed common shares in Oi closed down 6.78% on Monday and Telefonica Brasil shares closed down 2.47%. Brazil's benchmark Bovespa equities index fell 0.45%.

($1 = 5.11 reais) (Reporting by Carolina Mandl Additional reporting by Gram Slattery and Daina Beth Solomon Editing by Chris Reese, Alexander Smith and Sonya Hepinstall)