KIGALI, Rwanda — Human rights groups are criticizing Rwanda’s electoral commission’s announcement that it must approve any social media messages of candidates in the August presidential election.

Human Rights Watch on Thursday called the new law a blatant attack on freedom of expression.

The government-backed National Electoral Commission says candidates risk having their social media accounts blocked if they violate the law.

The decision has attracted criticism from many opposition members and Western diplomats. U.S. Ambassador Erica Barks-Ruggles has called it a serious limitation on freedom of expression.

The Rwanda Utilities Regulatory Authority says the electoral commission does not have the mandate to regulate or interrupt the use of social media by citizens.

Four candidates have expressed plans to challenge longtime President Paul Kagame. Critics say he does not tolerate opposition.