(Bloomberg) -- The chief of staff and potential successor to Democratic Republic of Congo President Felix Tshisekedi is under provisional arrest as part of a corruption investigation, fracturing his administration and throwing the country’s political class into turmoil.

Authorities detained Vital Kamerhe Wednesday after he appeared at a hearing on state corruption, police spokesman Colonel Pierrot Mwanamputu said Thursday by phone from the capital, Kinshasa. Kamerhe is being held at the city’s Makala prison and hasn’t been charged.

“It’s very rare in the DRC to see very senior officials, especially someone as visible and well known as Vital, be held accountable for corruption, so this is highly symbolic,” said Stephanie Wolters, senior research fellow at the South African Institute of International Affairs. “This throws a bomb into Tshisekedi’s relationship with his alliance partner.”

Former opposition leader Tshisekedi was the surprise winner of an election in 2018 in which he was backed by Kamerhe, after they agreed that Kamerhe would succeed the president when the next vote is held in 2023. One of their main campaign pledges was to reduce rampant state corruption that has helped keep the world’s biggest cobalt producer one of the poorest nations.

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Kamerhe, from Congo’s eastern province of South Kivu, has been a powerful player in the country’s politics for more than 15 years. He helped lead former President Joseph Kabila’s first presidential campaign in 2006, after which he became president of the National Assembly. Kamerhe broke with Kabila over the latter’s handling of the conflict in eastern Congo in 2009. He then ran for president against his former boss in 2011, finishing third.

The future of the alliance between Kamerhe and Tshisekedi’s political parties is now in doubt, amid an investigation by a public prosecutor in Kinshasa into the use of hundreds of millions of dollars meant for infrastructure projects during Tshisekedi’s first 100 days in office.

“Whether this is a way of getting rid of a political rival or an attempt to be tough on corruption will be determined by whether members of Tshisekedi’s party and inner circle are eventually investigated and held accountable,” Wolters said.

Lawmakers from Kamerhe’s Union pour la Nation Congolaise, or UNC, said they “deplored the arrest and arbitrary detention” of their leader and called for his immediate release.

The accusations of corruption “are totally false,” they said in a statement. “Nothing indicated that Honorable Vital Kamerhe was a flight risk in order to justify his arrest and detention.”

Tshisekedi’s spokesman, Kasongo Mwema Yamba Yamba, declined to comment, saying only: “Justice is independent.”

Congo, Africa’s third-most populous nation, is struggling to fight the coronavirus pandemic and has already cut its economic growth projections for the year from 4.1% to 1.1%. The country has recorded 207 cases of Covid-19 and 20 deaths from the virus through Wednesday, according to the agency responding to the pandemic.

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