The foreign ministry never gave details on the eight Indian nationals or their alleged crimes, and Qatar has not commented on the case or made the charges public.

But Indian media have reported that the men -- among them former high-ranking and decorated officers, including captains who once commanded warships -- were arrested in Doha in August 2022.

In October, India said it was "shocked" after a Qatari court had sentenced them to death, but the sentence was reduced in December.

The eight men were employees of Al Dahra, a Gulf-based company that offers "complete support solutions" to the aerospace, security and defence sectors, according to its website.

The Hindu newspaper reported the men were spying for a "third country", while the Times of India has said that "various reports claimed they were accused of spying for Israel".

On Monday, New Delhi said the men had all been released.

"The Government of India welcomes the release of eight Indian nationals working for the Dahra Global company who were detained in Qatar," the foreign ministry said in a statement.

"Seven out of the eight of them have returned to India," it added, thanking Qatar's Emir Sheikh Tamim bin Hamad Al Thani for the decision "to enable the release and homecoming" of the detainees.