UEFA are unhappy about the state of pitches at Euro 2016 and are working to improve them as the championship enters its second week, tournament director Martin Kallen said on Friday, reports Sky Sports.

Some stadiums are hosting six games and wet weather across France is visibly having an impact.

"The pitches should be better and we're not happy," Kallen told reporters.

"We have taken measures to preserve pitches but in a summer tournament you don't expect it to rain so much."

With the exception of the Parc des Princes in Paris and Lens' Bollaert-Delelis, which are used only for football, all the Euro 2016 stadiums have multiple uses with owners maximising commercial activity in them.

"Pitches are a major issue in modern stadiums because they are multifunctional arenas," Kallen said.

UEFA have in the past opted to relay a pitch during a European Championship.

Kallen said that could be done again if needed.

"We had no choice but to replace the pitch. The risk was enormous," he said.