The US embassy in India has revoked and denied visas of some Indian business executives and corporate leaders over their alleged involvement in trafficking fentanyl precursors.

Fentanyl precursors are chemicals used to produce a synthetic opioid that has been a leading cause of overdose deaths in the US.

The embassy said in a statement on Thursday that "these individuals and close family members may be ineligible for travel" to the US. It also said it would subject executives connected with companies known to have trafficked fentanyl precursors to heightened scrutiny if they applied for visas.

The embassy did not name those affected, but confirmed they were Indian nationals.

"The US embassy in New Delhi is committed to fighting illicit drug trafficking," said chargé d'affaires Jorgan Andrews. Those involved, and their families, may face "consequences that may include being denied access to the United States".

The US embassy said the action was taken "in furtherance to the Trump administration's efforts to keep Americans safe from dangerous synthetic narcotics" and was was legally backed by the provisions of the Immigration and Nationality Act.

It described stopping the flow of fentanyl and its precursors as a top priority and expressed gratitude to Indian officials for their "close cooperation to combat this shared challenge".

In January, the US Department of Justice said it had charged two India-based companies, Raxuter Chemicals and Athos Chemicals, along with Bhavesh Lathiya, a senior executive of Raxuter Chemicals, with conspiring to distribute and import fentanyl precursor. Mr Lathiya was arrested on 4 January.

In March, federal prosecutors in Washington also charged Vasudha Pharma Chem Ltd and three of its senior employees with illegally manufacturing and distributing fentanyl precursors, the US Drug Enforcement Administration said in a press statement.

In a statement to the US Congress this week, Trump named India among 23 major drug transit or illicit drug-producing countries, while noting the list did not reflect governments' counter-drug efforts.