India's federal police said four people linked to a network of human traffickers have been arrested, accused of luring young men to Russia with the promise of lucrative jobs or university admissions only to force them to fight in the war in Ukraine.

About 35 Indian men were duped in this manner, the Central Bureau of Investigation (CBI) said in March.

The four Indian nationals arrested were a translator, a person facilitating visa processing and the booking of airline tickets as well as two "main recruiters" for the southern states of Kerala and Tamil Nadu, the CBI said on Tuesday.

The investigation "is continuing against other accused persons who are part of this international network of human traffickers," the CBI said.

The families of two Indian men who were killed in the war have told Reuters they had gone to Russia expecting to work as "helpers" in the army.

India's foreign ministry says each case has been "strongly taken up" with Russia. Moscow has not responded to repeated requests from Reuters for comment.

India has refused to condemn Russia over the war, calling instead for dialogue and diplomacy to end the conflict. The two countries have enjoyed a close relationship for decades, trading in items from fighter jets to tea.

India has also increased its purchase of cheap Russian oil since the war, with Moscow emerging as its top oil supplier in the last financial year for the second year in a row. (Reporting by Sakshi Dayal; Editing by YP Rajesh and Edwina Gibbs)