SAO PAULO--Brazil's telecommunications regulator has opted to suspend sales by three mobile phone companies in some states because of the volume of customer complaints, the Folha de Sao Paulo newspaper reported on its web site on Tuesday.

The regulator, known as Anatel, will from Wednesday suspend mobile phone sales by TIM Participacoes SA (TSU, TIMP3.BR), a unit of Telecom Italia SpA (TI, TIA, TIT.MI), Oi SA (OIBR, OIBR4.BR) and Claro, a unit of Mexico's America Movil SA (AMX, AMOV, AMX.MX), according to the report.

TIM won't be allowed to sell in 15 states, Oi in six states and Claro in three states, according to the report, which didn't disclose which states would be affected.

Anatel has called a press conference for later on Tuesday afternoon "to discuss the quality of mobile phone service in Brazil." A spokesman for Anatel declined to comment on the Folha article.

The companies will only be allowed to restart sales once they present an investment plan for the next two years, with goals to resolve problems with the quality of the service they're providing to customers, according to Folha.

Together, the three account for around 70% of the Brazilian mobile phone market; Telefonica Brasil SA (VIV, VIVT4.BR) is the fourth operator, with the remaining 30% share.

Anatel has been monitoring performance over the last six months, according to the report.

Shares in the two locally-traded firms to be affected, TIM and Oi, were down 2.4% and 3.5%, respectively, while the broad Ibovespa index was up 1.1% on the day. Shares in Telefonica Brasil were up 0.6%.

New York-traded shares in America Movil were down 1.1%.

Write to Matthew Cowley at matthew.cowley@dowjones.com

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