(Recasts with Avianca Brasil response)
SAO PAULO, Dec 7 (Reuters) - Brazil's fourth largest airline Avianca Brasil said on Friday it had been served with an injunction which newspaper Valor said could force the carrier to surrender 11 planes, or close to 20 percent of its fleet, to lessors.
A representative for Avianca Brasil said the carrier did not think an appeal would be necessary as it was trying to reach an out-of-court agreement with the airplanes' owners.
The company decided in August to reduce its fleet by eight planes and has started renegotiating its plane leases to carry out the plan, it said in a separate statement.
According to Valor, leasing companies BOC Aviation and Constitution Aircraft filed for the injunction. The planes include Airbus A320s, the newspaper reported.
Avianca Brasil is unlisted and independent from the larger and better-known Avianca Holdings SA, a publicly traded airline company based in Colombia.
Both airlines are owned by a holding company controlled by German Efromovich, a Bolivian-born investor who last week sealed a personal loan of $456 million with U.S.-based United Continental Holdings.
The loan is secured by Efromovich's shares in Colombia's Avianca, which is more profitable than its Brazil counterpart but which also has a significant amount of debt.
It is unclear how Efromovich will spend the loan, but failing to repay his debt could pave the way for United to take control of Colombia's Avianca.
United is already expanding in Latin America through a code-share deal with Avianca and Panama's Copa, but an ownership stake in Avianca would give the No. 3 U.S. airline unprecedented access to the Latin American market. (Reporting by Marcelo Rochabrun Editing by Frances Kerry and Richard Chang)