Father Stan Swamy, a jailed Jesuit priest and long-time Indian tribal rights activist, died in the western Indian city of Mumbai aged 84.

His lawyer and doctor told the Bombay High Court that Fr Swamy, who suffered from Parkinson’s disease, died of cardiac arrest.

The court was hearing a plea for bail on medical grounds after Fr Swamy had been denied bail in March.

The activist had been moved to a private hospital from Tajola Central Prison in May after his health began rapidly deteriorating.

He was admitted to the ICU, where he tested positive for Covid-19.

“Stan worked to light the world and do away with injustice.

“The government may have succeeded in snuffing his life out, but his spirit will continue to inspire,” Father Jerome Stanislaus D’souza, the president of Jesuits in India, said in a statement.

In October, Fr Swamy was arrested in the eastern state of Jharkhand after being charged under India’s harsh anti-terror law, the Unlawful Activities (Prevention) Act.

He was the oldest person to be accused of terrorism in India.

The government’s National Investigation Agency arrested him and 15 other activists and academics over a 2018 incident in which violence broke out between low-caste Dalits and right-wing groups.

Authorities alleged that those arrested had links to Maoist rebels, who are active in several states and are considered the country’s biggest internal security threat.

Fr Swamy maintained his innocence and rejected any links to the rebels, saying he was targeted over his work and writings on caste injustice and struggles faced by marginalised groups.

His arrest sparked widespread outrage in India, with many prominent opposition politicians and academics demanding his release.

The anti-terror law was amended in 2019 to allow the government to designate an individual as a terrorist.

Police can detain people for up to six months without producing any evidence, and the accused can subsequently be imprisoned for up to seven years.

Critics have called the law draconian, and accuse prime minister Narendra Modi’s government of using it to mute dissent.

Fr Swamy, who focused on empowering and uplifting India’s indigenous tribes, was known for tirelessly advocating for the rights of those most marginalised.

Tributes poured in on social media on Monday.

“He deserved justice and humaneness,” tweeted Rahul Gandhi, leader of the main opposition Congress party.

“Father Stan Swamy spent a lifetime working for the dispossessed and the disadvantaged,” wrote prominent historian Ramachandra Guha, calling his death “a case of judicial murder”.

In January, to mark 100 days in jail, Fr Swamy penned a letter thanking all those who had stood by him.

He said he had not met the 15 other people accused with him, despite being in the same jail.

“But we still sing in chorus.

“A caged bird can still sing,” he wrote.

In his last bail hearing in May, he predicted his death if he remained in jail.

“I would rather die here very shortly if things go on as it is,” Fr Swamy told the judges.

On Monday, his lawyer, Mihir Desai, told the court that Fr Swamy is not survived by any family members, the Live Law website reported.

“The Jesuits are his only family,” Mr Desai said.