WASHINGTON (AP) — The U.S. strongly criticized Cambodia on Friday for banning radio stations from carrying foreign-produced programming in the local Khmer language during the campaign for next month’s elections.

State Department spokesman Patrick Ventrell said Friday that’s a serious infringement of press freedom and such restrictions call into question whether the July 28 vote will be free and fair.

The election is almost certain to see Prime Minister Hun Sen, Asia’s longest-serving leader, extend his 28 years in power. His government is already accused of harassing political opponents. The Obama administration has said the exclusion of exiled opposition leader Sam Rainsy threatens the vote’s legitimacy.

The directive, dated Tuesday and signed by acting Information Minister Ouk Pratna, orders all FM stations to stop rebroadcasting radio programs from foreign stations through the monthlong campaign period that began Thursday, until election day. It threatens legal action if they fail to comply.

“This directive is a serious infringement of freedom of the press and freedom of expression and starkly contradicts the spirit of a healthy democratic process,” Ventrell told reporters at the State Department. He urged the Cambodian government to reconsider.

Radio Free Asia said its Khmer service has been dropped by 10 stations. It called the directive “the most sweeping and stunning frontal assault on media freedom in Cambodia in recent memory.”

Voice of America also condemned it, saying it deprives the Cambodian audiences of critical news and information on the election.

“These types of balanced and informative broadcasts are needed more than ever during the elections and we condemn any effort to silence the media,” VOA said in a statement.

Both of the Washington-based networks are U.S. government funded. They said they would continue broadcasts by shortwave radio, satellite and on the Internet.

Radio Australia, which also broadcasts in Khmer, would be affected too, Radio Free Asia reported. But foreign broadcasts from Voice of Vietnam and China Radio International and French public radio station RFI won’t be as they operate their own stations in Cambodia, the report said.

The iron grip on government held by Hun Sen’s party already gives him major advantages in the election, including influence over state-run and other mainstream media, the loyalty of the civil service and the power to dispense patronage.

In the last election, in 2008, the party won 90 of the 123 seats in the National Assembly. Two weeks ago, 28 opposition lawmakers were expelled from parliament on a technicality.