By Andrei Makhovsky
MINSK (Reuters) - Protesters formed a line up to 4 km (2.4 miles) long in Minsk, the Belarus capital, on Thursday evening after President Alexander Lukashenko's main rival was detained in a widening crackdown ahead of August's presidential election.
Lukashenko, who has allowed little dissent in the former Soviet republic since gaining power in 1994, faces the biggest challenge to his authority in years, with thousands taking to the streets to support opposition candidates.
Viktor Babariko, who is widely seen as Lukashenko's main challenger in the election, was detained after being accused of crimes including taking $430 million out of the country in money-laundering schemes.
Babariko was detained along with his 30-year-old son, Eduard, who was running his father's election campaign. Babariko's election team said authorities were also searching his home.
In Minsk, protesters took to the streets and passing cars honked their horns in solidarity for hours.
"We came to support a candidate for whom we were going to vote, who was illegally detained in order not to be allowed to run for election. The whole country wants change," said 50-year-old Gennady in the protest line.
Public frustration with Lukashenko's handling of the coronavirus crisis and grievances about the economy and human rights have reinvigorated opposition.
Babariko's campaign team said it would still field him in the presidential vote on Aug. 9.
"We consider the events of recent days and, in particular, today's detention and the barring of lawyers from access to Viktor and Eduard Babariko as a direct violation of human rights," the campaign team said in a statement. "What we hear about the criminal case and the detention from state television channels, we consider it an absurdity."
Lukashenko has denied allegations by Babariko of using criminal cases to exert political pressure on his opponent.
Babariko is a former head of the local unit of Russia's Gazprombank. Belgazprombank, whose offices were raided in a tax evasion and money laundering case, has been put into temporary administration and 15 workers detained.
Another election candidate said this week she was pressing on with her campaign, despite receiving a threat to have her children taken away.
(Writing by Matthias Williams; Editing by Giles Elgood, Alexander Smith and Leslie Adler)