A Turkish court has sentenced the mayor of Istanbul to more than two and half years in prison on charges of insulting members of the Supreme Electoral Council.

The court on Wednesday also imposed a political ban on Ekrem Imamoglu, a key opposition politician, which could lead to his removal from office in Turkey’s largest city.

Imamoglu called the sentence “political and unlawful”.

The popular mayor, who belongs to the main opposition Republican People’s Party (CHP), is seen as a key opponent of President Recep Tayyip Erdogan. The verdict was issued nearly six months ahead of presidential and parliamentary elections.

A jail sentence or political ban would need to be upheld in appeals courts, potentially extending an outcome to the case beyond the elections, which are due by June.

Al Jazeera’s Sinem Koseoglu, reporting from Istanbul, said the court of appeals may uphold the verdict, reverse it or it can decide on an entirely “different verdict”.

“But we expect Ekrem Imamoglu, even though he’s not going to be spending a night in jail, … he will be banned from politics,” Koseoglu said. “It will ban him from joining mayoral elections in 2024 and removing his membership from the main opposition party.”

Critics alleged the mayor’s trial was an attempt to eliminate a key Erdogan opponent ahead of the June presidential election.

“I have been speaking to people from the ruling AK [Justice and Development] Party, and even though they are against Ekrem Imamoglu, … they say this will not serve Erdogan,” Koseoglu said.

“Many argue that the aim is to ban him [Imamoglu] from the elections,” she said.

The US State Department said it was “deeply troubled and disappointed” by the jail sentence.

“This unjust sentence is inconsistent with respect for human rights, with respect to fundamental freedoms and rule of law,” said State Department principal deputy spokesperson Vedant Patel on Wednesday.

‘Foolishness’ comment

Imamoglu was elected mayor in March 2019. His win was a blow to Erdogan and his AK Party, which had controlled Istanbul for a quarter-century. The party pushed to void the municipal election results in the city of 16 million, alleging irregularities.

The challenge resulted in a repeat of the election a few months later, which Imamoglu won by a wider margin.

Imamoglu was charged with insulting senior public officials after he described cancelling the first mayoral election as an act of “foolishness”. The charge carried a maximum prison sentence of four years.

The mayor denied insulting members of the electoral council, insisting his words were a response to Interior Minister Suleyman Soylu. Soylu called Imamoglu “a fool” and accused him of criticising Turkey during a visit to the European Parliament.

Thousands of the mayor’s supporters protested against the verdict in front of the municipality building.

Kemal Kilicdaroglu, the leader of the CHP, cut short a visit to Germany to return to Turkey and lend his support to Imamoglu.

During the trial, the court heard testimony from Imamoglu’s press officer, Murat Ongun, and another aide who confirmed that the mayor’s words were in response to Soylu.

“Either before or after this event, or even on May 6 when the elections were canceled, I did not hear any negative words from Ekrem Imamoglu concerning the [Supreme Electoral Council] members,” the T24 news website cited Ongun as saying. “All of his statements were made towards political figures.”

But in a video posted on social media, Soylu insisted the mayor’s comments were directed at the council members, who canceled the elections.

The outcome of the 2023 election is seen as hinging on the ability of the CHP and other opposition parties to join forces around a single candidate to challenge Erdogan and the AK Party, which has governed Turkey for two decades.