New EU sanctions against Russia have gone into force, blocking loans for five big state banks and curbing EU business with oil and defence firms.
The aim is to keep pressure on Russia over its role in the Ukraine crisis. But the measures could be eased or lifted if a ceasefire in Ukraine holds.
Russian Foreign Minister Sergei Lavrov accused the EU of “taking a path towards undermining the peace process”.
Nato says Russia still has about 1,000 heavily armed troops in east Ukraine.
The EU sanctions will block the export of services and deep-water technology for Russia’s oil industry.
Three major Russian state oil firms are targeted: Rosneft, Transneft and Gazprom Neft, the oil unit of gas giant Gazprom.
Their access to financial markets will be restricted – a serious matter for Rosneft, which last month asked the Russian government for a $42bn (£25.2bn) loan.
Big Russian state-owned banks will be barred from getting loans with a maturity longer than one month, and from getting other financial services in the EU.