Countries thinking of leaving the International Criminal Court should instead work within the system to improve the court, a U.N. spokesman said Thursday

Farhan Haq said the U.N. is aware of reports that Philippine President Rodrigo Duterte is considering withdrawing his country from the International Criminal Court but that they have not yet received any formal communication from the Philippines. He urged them and other nations to reconsider.

“It’s clear from what the leaders have said that there are many, many governments who believe that there’s a problem. What we’re saying is what you do with that is you work to improve the system,” Haq said.

South Africa, Burundi and Gambia have announced plans to withdraw saying the court unfairly singles out African nations. So far all of the court’s trials have focused on crimes in Africa, though the majority of the cases were referred to the court by the African countries.

Russia, which is not an ICC member, snubbed the court with President Vladimir Putin signing a symbolic decree to withdraw from the court on Wednesday.

The U.S., China and Syria are among the nations that have not signed on to the court

Haq defended the Hague-based court which was established in 2002 as a “path breaking, international institution, one of the very first that can really hold different parties and even leaders accountable for the worst international crimes.”

“It deserves our whole hearted support. If there are problems with the court, if countries have any real grievance of a perception of bias, what we encourage is for them to work it out within the system,” he added.