BERLIN -- Russia sent significantly more oil and coal to India and China over the summer compared with the start of the year, while European countries that long relied on Russian energy have cut back sharply in response to the war in Ukraine, said a report published Tuesday.

The Centre for Research on Energy and Clean Air said Russia received about 158 billion euros (US$158 billion) in revenue for the sale of oil, natural gas and coal from February to August, more than half of which -- some 85 billion euros worth -- was exported to the European Union.

Within the EU, Germany was the biggest importer, buying 19 billion euros worth of fossil fuels from Russia during the six-month period.

The single biggest importer worldwide, however, was China, which bought 35 billion euros worth of Russian energy, the Helsinki-based group said.

While Russia's revenue rose, overall export volumes dropped by 18% compared with when the country invaded Ukraine, the report said.

The EU has cut its imports from Russia by 35% since the war began, with Russian coal now banned in the 27-nation bloc and a halt to oil sales due to take effect at the end of the year.

Russia itself has sharply cut flows of natural gas to the EU, indicating this week that they would not resume unless Western sanctions are lifted.

Germany's economy minister, Robert Habeck, said Monday that his country doesn't expect gas imports from Russia to resume anymore.

Foreign Minister Annalena Baerbock acknowledged Tuesday that past purchases of cheap Russian gas had come at the expense of Germany's national security -- an argument past governments in Berlin had firmly rejected.

"Until recently, there were spurious technical reasons; now the rulers in the Kremlin are alluding to our sanctions as a whole, which supposedly stand in the way of further gas deliveries," Baerbock said in a speech to German diplomats and business representatives in Berlin. "We must state this very clearly: We will not succumb to this blackmail."

Meanwhile, India and China imported significantly more coal and crude oil from Russia in July and August than in February and March, according to the report by the Centre for Research on Energy and Clean Air.

The group said fossil fuel exports contributed about 43 billion euros to Russia's federal budget, compared with independent estimates that the war has so far cost the Russian state the equivalent of 100 billion euros.