SAO PAULO, Sept 7 (Reuters) - TIM Participacoes, Telefonica Brasil and America Movil's Claro won the right to match any other higher bid for the mobile assets of Oi SA, the companies said in a securities filing on Monday.

Such a purchase agreement is known as "stalking horse" and acts as an opening offer that other interested bidders must surpass if they plan to buy the assets.

The telecoms trio has been in exclusive talks with Oi since Aug. 7, after presenting a joint 16.5 billion reais ($3.11 billion) bid for the company's cellular operations, including a long-term contract for the use of its fiber network valued at 819 million reais. Oi plans to auction that unit by year-end.

Oi, which filed for bankruptcy protection in 2016, is selling a series of assets to raise funds to repay creditors.

It will hold a creditor assembly on Tuesday to approve its amended plan, including the sale of its mobile assets.

($1 = 5.2995 reais) (Reporting by Carolina Mandl; Editing by Peter Cooney)