Wangchuk, 59, an environmental advocate who became a key figure in Ladakh's movement for greater autonomy, was held in September and later charged under India's National Security Act following protests that left four people dead and dozens wounded.

New Delhi had blamed the violence on "provocative speeches" by Wangchuk, who had been on a hunger strike demanding either full federal statehood for Ladakh or constitutional protections for its tribal communities, land and fragile environment.

Authorities in the sparsely populated, high-altitude region bordering China and Pakistan, at the time said the order, issued by the district magistrate of Leh, was needed to "maintain public order.

Under the stringent National Security Act, a suspect can be detained for up to 12 months without being formally charged.

The home ministry said in a statement Saturday it had decided to end Wangchuk's detention "with immediate effect" after "due consideration".

It is not clear if the charges against Wangchuk were dropped.

Mustafa Haji, a lawyer for the Leh Apex Body -- which spearheaded last year's protests -- said Wangchuk was released from jail in the western city of Jodhpur soon after.

The home ministry said it remained "committed to fostering an environment of peace, stability, and mutual trust in" Ladakh and have "meaningful dialogue with all stakeholders".

The decision also comes as the Supreme Court continues to hear a petition filed by Wangchuk's wife Gitanjali Angmo, challenging the legality of his detention.

The fate of that case remains unclear now that Wangchuk has been released.

An engineer by training, Wangchuk is best known for pioneering water conservation projects in the Himalayas.

He received the prestigious Ramon Magsaysay Award in 2018 for his environmental work and contributions to reforming local schooling in Ladakh.

His life and work are said to have inspired a character played by Bollywood star Aamir Khan in the hugely popular movie "Three Idiots".

Prime Minister Narendra Modi's government split Ladakh off from Indian-administered Kashmir in 2019, imposing direct rule on both.

Ladakh has since called upon New Delhi to include it in the "Sixth Schedule" of India's constitution and have their own local legislature to make their laws and policies.

India's army maintains a large presence in Ladakh, which includes disputed border areas with China.

Troops from the two countries clashed there in 2020, killing at least 20 Indian and four Chinese soldiers.