(Reuters) -White House trade adviser Peter Navarro said India's purchases of Russian crude were funding Moscow's war in Ukraine and had to stop, adding that New Delhi was "now cozying up to both Russia and China."

"If India wants to be treated as a strategic partner of the U.S., it needs to start acting like one," Navarro wrote in an opinion piece published in the Financial Times.

India's Foreign Ministry has previously said the country is being unfairly singled out for buying Russian oil while the United States and European Union continue to purchase goods from Russia. U.S. President Donald Trump an additional 25% tariff on Indian goods earlier this month, citing New Delhi's continued purchases of Russian oil, taking total tariffs on imports from India to 50%.

"India acts as a global clearinghouse for Russian oil, converting embargoed crude into high-value exports while giving Moscow the dollars it needs," Navarro said.

The adviser also said it was risky to transfer cutting-edge U.S. military capabilities to India as New Delhi was "now cozying up to both Russia and China."

Longtime rivals China and India are quietly and cautiously strengthening ties against the backdrop of Trump's unpredictable approach to both. Indian Prime Minister Narendra Modi is set to meet Chinese President Xi Jinping at the end of the month while Chinese Foreign Minister Wang Yi will visit India from Monday for talks on the disputed border between the two countries.

A planned visit by U.S. trade negotiators to New Delhi from August 25-29 has been called off, a source said over the weekend, delaying talks on a proposed trade agreement and dashing hopes of relief from additional U.S. tariffs on Indian goods from August 27.