Czech police said on Monday that an Indian citizen suspected of involvement in an alleged plot to kill a Sikh separatist in the United States had been extradited there.

The US Justice Department charged the man, identified as Nikhil Gupta, in November with plotting to assassinate a Sikh separatist leader on US soil.

It alleged an Indian government official was also involved in planning the plot to kill the person, a US citizen of Indian origin.

Many Sikhs support the Khalistan movement, that wants an independent homeland in the northern Indian province of Punjab, which Indian authorities strongly oppose.

The government has cracked down on the movement while denying involvement in the targeting of pro-Khalistan activists outside India.

"The foreigner suspected in the United States of an assassination plot has been in the hands of the US judiciary since Friday," Czech police said on X.

They added that Gupta was "safely extradited from a Prague airport," posting video images of the man being escorted into a plane.

Gupta was detained at Prague airport on June 30, 2023, under extradition orders issued by the US Justice Department.

The department said the man allegedly targeted in the killing "is a vocal critic of the Indian government and leads a US-based organisation that advocates for the secession of Punjab."

Indian Prime Minister Narendra Modi, who was elected to a third term this month, had vowed to "look into" the case while visiting the United States in late 2023.

India's foreign ministry has said it created a "high-level" inquiry committee to investigate the case.

US intelligence agencies have assessed that the plot on American soil was approved by India's top spy official at the time, Samant Goel, The Washington Post reported in April.

A similar case in Canada has meanwhile sparked a diplomatic row between Ottawa and New Delhi.

Canada arrested and charged four Indian nationals in May over their alleged role in the 2023 killing of Hardeep Singh Nijjar, a separatist Sikh leader, in Vancouver.

Nijjar, who immigrated to Canada in 1997 and became a citizen in 2015, had advocated for a separate Sikh state of Khalistan.

Wanted by Indian authorities for alleged "terrorism" and conspiracy to commit murder – allegations he denied – Nijjar was shot and killed on June 18, 2023, outside the Sikh temple he led in suburban Vancouver.

Canadian Prime Minister Justin Trudeau announced several months later that Canada had "credible allegations" connecting Indian intelligence to the slaying.

India dismissed the allegations as "absurd" and responded by briefly curbing visas for Canadians and forcing Ottawa to withdraw diplomats. (AFP)