G7 leaders meeting in Japan will discuss sanctioning Russia's billion-dollar diamond trade, an EU official said Thursday, hoping to further starve Moscow of funds for its war in Ukraine.

"We believe we need to limit exports from Russian trade in this sector," the official said, adding that the G7 was unlikely to reach a final agreement on the economically sensitive topic in Japan.

Russia exported almost $5 billion worth of diamonds in 2021, according to the Observatory of Economic Complexity, a trade data project linked to the Massachusetts Institute of Technology.

The United Arab Emirates, India and EU member Belgium were among the top importers.

The EU official said Indian buy-in would be vital to make sure any sanctions regime had maximum impact.

"We would like to engage in a dialogue with them, because the diamond industry is quite important in India, not necessarily in terms of numbers, but in terms of politics, symbolism," the official said.

India has close military ties to Moscow and has never condemned Russia's invasion of Ukraine.

Prime Minister Narendra Modi has been invited to the Hiroshima summit along with leaders of other major developing economies that the G7 wealthy democracies hope to sway on Russia and China.

G7 countries have levied unprecedented sanctions on Russia over the last year, but have trodden carefully in sectors that could hurt European economies still recovering from the Covid-19 pandemic.