The superintendence of Brazil’s competition regulator Cade said on Friday it viewed an asset sale by Brazilian telecom Oi SA as “complex,” suggesting that TIM, Telefônica Brasil and América Móvil’s Claro may struggle to wrap up a quick sale.

The three companies won an auction to buy Oi’s mobile network operations for 16.5 billion reais ($3.17 billion) in December, pending regulatory approval, after Oi filed for bankruptcy protection in 2016.

The decision by Cade’s superintendence informs whatever final move the full board of the regulator may give.