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Aug 11 (Reuters) - Mobile service provider NII Holdings Inc , reporting its ninth quarterly loss in a row, said on Monday it may have to file for bankruptcy after struggling to compete in Brazil and Mexico.
NII shares fell more than 50 percent in after-market trading to 30 U.S. cents, after ending regular trade at 66 cents on the Nasdaq.
"Despite the actions we've taken to improve our operational performance, we have fallen short in our efforts, leaving the company with a liquidity position that is not sufficient to support the business," Chief Executive Steve Shindler said in a statement.
NII, which in March hired financial firms to advise on a potential sale of the company, said it will not be able to continue to operate unless it can "restructure debt obligations, find a strategic solution or some combination of those approaches."
In March, the company said it hired UBS Investment Bank to explore options that could also include partnerships as well as the sale or merger of one or more of its business units.
The company, which operates in Latin America under the Nextel brand, ended the second quarter with a net debt of $4.8 billion and with $1 billion in cash and investments.
NII said on Monday it is taking more aggressive actions to cut costs and balance investments and is in talks with creditors to restructure debt.
The company said, in its annual regulatory filing in February, it believed it had sufficient funds to meet its obligations through 2014 but was unlikely to have enough funds for next year.
NII is facing intense competition in Brazil and Mexico - its largest markets.
The company is struggling to stem customer losses as its higher-paying corporate customers are lured away by Telefonica Brasil SA and Mexican billionaire Carlos Slim-controlled America Movil with their unlimited plans and faster and bigger networks.
NII said earlier this year it lost customers in Mexico, its second-biggest market, because of problems with its roaming services after Sprint Corp, from which it licenses the Nextel brand for Latin America, shut its iDEN network in the country last June.
NII's quarterly loss widened to $623.3 million, or $3.62 per share, from $396.4 million, or $2.30 per share, a year earlier.
The company lost 77,000 subscribers in the quarter ended June 30 and average revenue per subscriber fell to $28 from $36 a year earlier.
Operating revenue fell 23 percent to $968.8 million.
Analysts expected a loss of $2.30 per share on revenue of $948.1 million, according to Thomson Reuters I/B/E/S.
NII said that because of the ongoing review of its restructuring options it will not hold a conference call this quarter. (Reporting by Soham Chatterjee in Bangalore; Editing by Feroze Jamal and Steve Orlofsky)