MINSK (Reuters) – Security officials in Belarus on Thursday raided the local unit of Russia’s Gazprombank, which until recently had been headed by one of President Alexander Lukashenko’s main rivals in a presidential election due in August.

A spokesman for the State Control Committee said the raid was connected to an investigation into tax evasion. Officials at Belgazprombank were not immediately available for comment.

Presidential challenger Viktor Babariko told reporters that the purpose of the searches was to put pressure on him.

Lukashenko has ruled the ex-Soviet country with an iron fist since 1994 but has faced protests in recent weeks as unhappiness with his presidency was exacerbated by public anger over his decision not to impose a lockdown to halt the novel coronavirus pandemic.

Babariko resigned as head of Belgazprombank to launch his bid for the presidency. He vowed to continue his political fight on Thursday.

“The only right … response to the lawlessness is the continuation of our actions, the continuation of our struggle,” he said.

The authorities also detained blogger Sergei Tikhanouski who helped lead protests against Lukashenko and whose wife planned to run against the president. Charged with disrupting public order, Tikhanouski faces three years in prison.

Lukashenko has accused the opposition of trying to destabilise Belarus, which he said could lead to a “massacre on a square.”

Thousands of people across the former Soviet republic of 9.5 million have been lining up at election meetings to show support for people seeking to run against Lukashenko.

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

Lukashenko has dismissed fears about the virus as a “psychosis”. He rejected calls for a lockdown or social distancing measures, and instead suggested remedies such as drinking vodka or visiting saunas.

Belarus reported 51,816 coronavirus cases as of June 11, including 293 deaths.