The European Union's chief executive will on Tuesday announce a phased oil embargo on Russia for waging war in Ukraine, as well as hitting more Russian banks with sanctions, in the bloc's latest effort to isolate Moscow.

European Commission President Ursula von der Leyen is due to announce the measures, which must still be agreed by EU governments, after 0630 GMT in an address to the European Parliament in Strasbourg.

The Commission's proposed measures against Russia, which attacked Ukraine by land, sea and air on Feb. 24, are likely to include phasing out supplies of Russian crude oil within six months, sources said.

As well as oil, the sixth round of sanctions would also affect Sberbank, Russia's top lender, diplomats told Reuters, adding it to several banks that have already been excluded from the SWIFT messaging system.

If agreed, the sanctions would mark a watershed for the 27 countries long dependent on Russian energy. There would still be exemptions for some countries, including Hungary and Slovakia, and natural gas has yet to be targeted with sanctions.

Its ban has not yet been properly discussed at EU level because of the bloc's reliance on it.

(Reporting by Robin Emmott, John Chalmers, Sabine Siebold)