India's Financial Crimes Authority has arrested a top opposition leader hours after he resigned as chief minister of Jharkhand state.
Hemant Soren of the Jharkhand Mukti Morcha (JMM) party has been accused of corruption. He denies the allegations.
He was arrested by law enforcement on Wednesday evening after seven hours of interrogation.
His party has named Transport Minister Champai Soren as the eastern state's next prime minister.
Mr Soren has challenged his arrest in India's Supreme Court, calling it politically motivated. The matter will be heard on Friday.
He is the latest in a long list of opposition leaders to face high-profile investigations by India's central authorities.
The case against Mr Soren relates to a property he allegedly owns in the city of Ranchi, the capital of Jharkhand.
The ED alleged that he acquired the property from “proceeds of crime” by illegally selling land owned by the Indian Army.
Mr Soren denies the allegation and claims the property was “falsely claimed to be his”.
According to reports, the ED officials summoned Mr. Soren several times, but he refused to appear for questioning.
On Monday, officers reached Mr Soren's residence in the capital Delhi but discovered he was “missing”. The agency said it seized 3.6 million rupees ($43,381; £34,202) and a car from the house.
A day later, Mr. Soren showed up in Ranchi and said he would record his statement before the agency on Wednesday.
A curfew was imposed within 100 meters of the Prime Minister's residence and the ED office in Ranchi on Wednesday evening.
A few hours later, Mr. Soren tendered his resignation, after which his loyalist Champai Soren was named the next prime minister. Hemant Soren was arrested later that night.
The JMM described the investigation against Mr. Soren as a politically motivated “witch hunt.”
The party accused the federal government, led by Prime Minister Narendra Modi's Bharatiya Janata Party (BJP), of using central authorities to target opposition leaders ahead of the general election. The BJP, meanwhile, rejects allegations of political interference.
India's main opposition Congress party also condemned Mr. Soren's arrest, calling it a “blow to federalism.” The JMM is part of INDIA, the Congress-led coalition of opposition parties seeking to contest the elections against the ruling BJP-led National Democratic Alliance.
“The corruption-riddled BJP is waging a campaign to destroy democracy,” Congress leader Rahul Gandhi wrote on X (formerly Twitter).
Several other prime ministers and opposition leaders face corruption allegations.
In November, the ED had summoned Delhi Chief Minister Arvind Kejriwal in connection with a case related to a now-abolished alcohol policy in the state. His party leaders Manish Sisodia and Sanjay Singh have already been arrested in the case.
The ED is also probing money laundering allegations against the chief ministers of three southern states of Telangana, Kerala and Andhra Pradesh. All leaders have denied the allegations made against them.
Read more India stories from the BBC:
“Beer maven. Creator. Tv fanatic. Internet scholar. Award-winning web junkie. Avid alcohol expert. Friendly writer. Gamer.”