(Reuters) - Britain's Foreign Secretary William Hague warned Russia on Monday that the European Union was ready to impose more sanctions over the crisis in Ukraine if necessary.

Speaking ahead of a meeting in Luxembourg of EU foreign ministers, Hague said the bloc's 28 member states would likely want to see how Moscow responded to Ukraine's peace plan and a unilateral ceasefire, before making any decisions.

Later in the week, EU leaders hold a summit in Brussels and could take decisions on sanctions.

"(Russian president Vladimir) Putin should be in no doubt that in the EU we are ready to take those measures," Hague told reporters. "A lot of work has gone on preparing wider sanctions on Russia."

"That is for decision on Friday. I think by Friday we will be able to see how Russia is responding to the peace plan," he said.

The EU has already imposed several rounds of sanctions against Russia over its actions in Ukraine but it has shied away from agreeing significant economic measures, with some member states worried about antagonizing a major energy supplier.