President Donald Trump threatened Monday to "substantially" hike US tariffs on goods from India over its purchases of Russian oil -- a key source of revenue for Moscow's war on Ukraine.

Trump's heightened pressure on India comes after he signaled fresh sanctions on Moscow if it did not make progress by Friday towards a peace deal with Kyiv, more than three years since Russia's invasion.

Moscow is anticipating talks with the US leader's special envoy Steve Witkoff, who is expected to meet President Vladimir Putin this week.