MINSK (Reuters) – The leader of Belarus, Alexander Lukashenko, on Friday accused his political rival Viktor Babariko of corruption but denied trying to block Babariko from standing against him in the presidential election in August.

Lukashenko has ruled the eastern European country with an iron fist since 1994 but faces the biggest challenge to his authority in years, with thousands of people taking to the streets recently to support opposition candidates.

Public frustration with Lukashenko’s handling of the coronavirus pandemic and grievances about the economy and human rights have reinvigorated opposition to his rule.

Babariko, seen as Lukashenko’s most serious rival, is the former head of the local unit of Russia’s Gazprombank, whose offices were raided on Thursday in a tax evasion case.

Babariko, who denies allegations of corruption, said the raid was designed to put political pressure on him. Lukashenko denied that the criminal case was related to the election, but he said Babariko could not wash his hands of the allegations and blame other officials at the bank.

“What struck me most is that this scoundrel, I cannot call him otherwise, says: ‘I have nothing to do with this. They are the ones to blame’,” Lukashenko was cited by the state news agency BelTA as saying. “Look, they were not only his deputies. They are one gang.”

Belgazprombank said on Thursday that it was continuing normal operations and that its financial stability had not been affected.

On Friday, Russian shareholders of the bank, Gazprom and Gazprombank, published a joint statement, saying the management board of Belgazprombank had made new appointments on Thursday, calling the move “illegal”.

They said the shareholders plan to defend their interests “by all the available legal means” and they are making efforts to “safeguard financial stability of the bank”.

Russia and Belarus, usually seen as allies, have been engaged in a number of rows recently, including over oil and natural gas supplies.