ANKARA, Turkey (AP) — Turkey’s electoral authorities on Tuesday denied the newly elected mayor from a pro-Kurdish political party the right to hold office in an eastern city and replaced him with his runner-up in the race — a candidate from President Recep Tayyip Erdogan’s ruling party.

Sunday’s local polls were a blow to Erdogan and his Islamic-oriented Justice and Development Party after their wins last year in the presidential and parliamentary elections.

The main opposition party retained its hold of Istanbul and the capital of Ankara and made huge gains elsewhere while the pro-Kurdish Equality and Democracy Party, or DEM, won several municipalities in Turkey's mainly-Kurdish regions despite despite years of repression and thousands of political activists arrested.

The decision to revoke the mandate of Abdullah Zeydan, from DEM, after he won in the eastern city of Van, sparked condemnation and street protests on Tuesday. Police used a water cannon and tear gas to disperse the demonstration in Van. DEM said it would seek to appeal the decision.

The main opposition center-left Republican People’s Party, or CHP, also condemned the move and dispatched a delegation from the party to Van in a show of support to Zeydan.

In revoking his mandate, the electoral authority cited a last-minute court decision that reversed an earlier court ruling that said the politician, who spent time in prison, could run for office.

Zeydan won 55% of the votes in Van in Sunday's balloting. The second-placed candidate, Abdullah Arvas of Erdogan’s Justice and Development Party, garnered 27%.

In addition to Van, DEM won the municipalities of nine provinces in Turkey’s mainly-Kurdish populated southeast.

Over the past years, Erdogan’s government had removed elected pro-Kurdish mayors from office for alleged links to Kurdish militants and replaced them with state-appointed trustees.