The European Commission expressed concerns about the way Poland allocated 4G spectrum before and after its long-running auction held last year, and is seeking clarifications.

The auction, which ended last October, raised PLN9 billion ($2.34 billion) for the state, with four operators – Orange, T-Mobile, Polkomtel’s Plus and Play (P4) – acquiring spectrum in the 800MHz and 2.6GHz bands.

Lasting a total of seven months, the auction process was however not without controversy, with operators arguing that poor preparation led to a lengthy duration.

They also hit out at the government’s decision to change the rules while it was ongoing, and implement a deadline to end the auction.

Smaller operator Sferia, meanwhile, was awarded a block in the 800MHz band before the auction took place, leading to a complaint to the commission by T-Mobile.

An EC spokeswoman told Reuters it has decided to send a formal letter of notice to Poland in regards to its allocation of spectrum, and could reportedly take further action if it is not satisfied with the government’s response.

“The commission has concerns that the assignment of the 800MHz band to mobile operator Sferia did not respect EU rules on spectrum,” she said. “The commission also has concerns that Poland’s law on spectrum infringes on telecoms law.”

Poland reportedly has two months to reply to the notice.