Indian opposition leader Rahul Gandhi was detained by police on Tuesday while participating in protests with members of his party, the Congress.
They were protesting in capital Delhi while party president Sonia Gandhi was being questioned by a government agency that investigates financial crimes.
She and Rahul Gandhi have been accused of misusing party funds to acquire valuable real estate through a convoluted financial deal.
The Gandhis deny the allegations.
They have accused the governing Bharatiya Janata Party (BJP) of using federal law enforcement agencies for political vendetta.
This was the second time Mrs Gandhi was questioned in connection with the case.
Before he was detained, Mr Gandhi and other party members sat on a road in Delhi, surrounded by dozens of police men, protesting against issues ranging from inflation to the alleged targeting of opposition leaders.
After about an hour, he and several others were taken in a bus to a detention centre.
In June, Rahul Gandhi was questioned for around 50 hours over five days by the ED in the same case. Mrs Gandhi was initially called for questioning at the same time, but her summons had to be deferred after she tested positive for Covid-19.
The 75-year-old leader was admitted to hospital and was discharged later in June.
This is the first time that Mrs Gandhi is being questioned by a federal law enforcement agency. BJP leaders have denied accusations by Congress party leaders that they are misusing federal institutions to settle political scores.
The case against the Gandhis has been brought by Subramanian Swamy, a BJP politician who accuses them of misappropriating party funds to buy a firm that published the now-defunct National Herald newspaper.
The National Herald newspaper was started in 1938 by Jawaharlal Nehru, India’s first prime minister and Rahul Gandhi’s great grandfather.
The newspaper was published by Associated Journals Limited (AJL) which was founded in 1937 with 5,000 other freedom fighters as its shareholders.
In 1947, when India won independence, Nehru resigned as chairman of the board of the newspaper after taking over his role as PM.
But the Congress party continued to play a huge role in shaping the newspaper’s ideology. Some of India’s best-known journalists have worked at the daily, which continued to be funded by the Congress party.
The newspaper ceased operations in 2008 for financial reasons. In 2016, it was relaunched as a digital publication and is now widely seen as a Congress mouthpiece.
Mr Swamy has alleged that the Gandhis used Congress party funds and took over AJL to try to acquire real estate assets in several cities, including Delhi and Mumbai, which are worth more than 20bn rupees ($250 million; £208 million).
The party has denied this, describing it as “a strange case of alleged money laundering without any money”.
