Fugitive jeweller Mehul Choksi has been arrested in Belgium, a source with India’s Enforcement Directorate told Reuters, seven years after details of his involvement in one of India’s biggest bank frauds became public.

The Indian government had sent a request for Choksi’s extradition prior to his arrest, but he is likely to challenge it on medical grounds, the source added.

Punjab National Bank (PNB), India’s second largest state-run lender by assets, had announced in 2018 that it had discovered alleged fraud worth $1.8 billion at a single branch in Mumbai.

The bank had filed a criminal complaint with India’s federal investigative agency against several entities, including billionaire jeweller Nirav Modi and Choksi, his uncle and the managing director of Gitanjali Gems, saying they had defrauded PNB.

Indian federal police filed fraud charges against Choksi, Nirav Modi and others in connection with suspected involvement in fraudulent transactions that led to huge losses for PNB.

The two diamond tycoons have denied any wrongdoing.

Choksi said in a letter in 2018 that the “investigating agencies were acting with pre-determined minds and interfering with the course of justice.” Reuters was unable to immediately contact his lawyer on Monday.

Nirav Modi fled India in 2018 before details of his alleged role in the case became public. He was arrested in Britain in 2019 and remains in custody there, although he has lost one extradition appeal.

Last week, a Pakistani-born Canadian businessman accused of helping orchestrate the 2008 attacks in Mumbai landed in New Delhi after the US extradited him in the first such transfer in a terrorism case.