One of AmBev's minority shareholders has questioned the company's merger with Interbrew.

The state-run Banco do Brasil's pension fund Previ, which owns 14.7% of AmBev's non-voting stock and 8% of its total capital, plans to ask securities regulators to look into the global merger between AmBev and Interbrew, announced last week.

Previ claims to have lost around 600m reals (US$206.4m) on its stock since the agreement was confirmed.

AmBev's ordinary voting shares, which will receive a premium price as part of the deal, have climbed by 15% 1 March, two days before the deal was announced. Non-voting stock, however, has tumbled by 33% over the same period.

Speaking to Dow Jones, Previ's investment director, Luiz Aguiar, said: "We're going to ask the CVM (Brazil's securities regulator) to look into this next Tuesday." He added that regulators should also ask AmBev and its advisor, Citibank, to move faster in making important documents available to the public.

A number of minority shareholders have complained that the Americas assets acquired by AmBev were overvalued. Under Brazilian law, however, controlling shareholders are allowed to negotiate a premium price for their shares.