Turkey’s government said Monday that it had indicted three popular mayors from Kurdish-majority provinces on terrorism charges and replaced them with state officials.

The suspension came five months after the mayors won landslide victories in local polls. Opposition parties criticized the move as anti-democratic, saying it was the latest evidence that President Recep Tayyip Erdogan’s government is intent on marginalizing pro-Kurdish voices.

The mayors of Diyarbakir, Mardin and Van are members of the opposition Peoples’ Democratic Party, or HDP, a pro-Kurdish party. Between them, they won nearly a million votes in local elections held in March — easily defeating candidates from Erdogan’s ruling Justice and Development Party, or AKP.

Erdogan has frequently accused the HDP of links to the militant Kurdistan Workers’ Party, or PKK, which has fought a decades-long insurgency against the Turkish government. HDP officials have denied such links. Dozens of HDP members have been arrested in the past three years, including mayors who were replaced with state administrators.   

“This is a new and clear political coup,” the HDP said in a statement. “It also constitutes a clearly hostile move against the political will of the Kurdish people.”

The Interior Ministry said the mayors — Ahmet Turk, Adnan Selcuk Mizrakli and Bedia Ozgokce Ertan — are accused of several crimes, including forming an armed terrorist organization and spreading propaganda for a terrorist group. The lengthy ministry statement said the PKK had used some Turkish municipalities as “logistical centers” to procure funding and equipment to support terrorism.

The Interior Ministry also announced that it had arrested more than 400 people across Turkey for purported links to the PKK as part of the government’s multi-front war against the militant group.

Turkey’s military has repeatedly attacked PKK positions in northern Iraq and threatened an offensive into northern Syria against a U.S.-allied Syrian-Kurdish force with links to the group.

But Turkey’s leaders had other reasons to move against opposition-party mayors at home, analysts said. The AKP suffered humbling defeats across Turkey in the local elections, including the losses of mayoral seats in Istanbul and Ankara. Some of the newly elected mayors — including Mizrakli, the Diyarbakir mayor — promised to investigate the financial dealings of ruling-party members who had previously held the posts.

The AKP fought doggedly to keep the mayor’s seat in Istanbul, Turkey’s largest city and its financial center. After initial election results showed that Ekrem Imamoglu, a challenger from the opposition Republican People’s Party, had won the seat, the ruling party appealed the results.

Imamoglu easily won a revote in June — a result that was hailed as a victory for democracy and that handed the opposition a high-profile platform from which to scrutinize the government’s policies.

In a Twitter post Monday, Imamoglu criticized the replacement of the three mayors. The move “cannot be explained by democracy or democratic practices,” he wrote. “Ignoring the will of the nation is unacceptable.”