Truss's comments follow remarks by Daleep Singh, U.S. Deputy National Security Adviser for International Economics, who said Washington will not set any "red line" for India on its energy imports from Russia.

"I think it's very important that we respect other countries' decisions about the issues that they face; India is a sovereign nation. I'm not going to tell India what to do," Truss told reporters.

Since Western sanctions were imposed on Russian entities after Moscow invaded Ukraine, India has bought at least 13 million barrels of Russian crude oil, compared with about 16 million barrels for all of last year, according to Reuters data.

Russia is offering a discount of $35 a barrel to price levels prior to the start of the Ukraine crisis in February, Bloomberg reported on Thursday.

Indian Oil Corp (IOC.NS) has a contract with Russian oil company Rosneft (ROSN.MM) that gives India's top refiner an option to buy up to 2 million tonnes, equivalent to about 15 million barrels, of Urals in 2022.

"I think it's natural for countries to go out into the market and look for what are good deals for their people," India's foreign minister Subrahmanyam Jaishankar said.

"I am pretty sure if we wait two or three months and actually look at who are the big buyers of Russian gas and oil, I suspect the list won't be very different from what it used to be."

India counts Russia as a friendly nation and has not condemned its attack on Ukraine. India has abstained from voting on U.N. resolutions on the war.

Meanwhile, Truss advocated for more stringent sanctions on Russia relating to the ports, gold and energy sectors.