EU countries were scrambling on July 14 to agree a new round of sanctions on Russia, on the eve of a deadline that could weaken a key measure to tamp down Moscow's oil revenues.

EU ambassadors have failed to agree on the new package of sanctions against Russia. A decision is expected at the foreign ministers' meeting on 13 July.

"Every time we make a sanctions pact, it gets a little harder," said Danish Foreign Minister Lars Lokke Rasmussen.