The European Union (EU) decided to expand sanctions against Russia by adding 12 more people on the blacklist of travel ban and assets freeze, canceling the EU-Russia summit in June this year, said President of the European Council Herman Van Rompuy on Friday.

The decision was made by leaders of the bloc's 28 member states during their spring summit, where the focus has been transferred from traditional economic issues to the Ukraine crisis.

Though the EU did not publish the 12 people's names immediately, but some of them are high ranking Russian officials, said Van Rompuy at a press conference following the summit.

He added any of Russia's further step to de-stabilize Ukraine will have far-reaching consequences.

President of the European Commission Jose Manuel Barroso also told reporters that the commission has been "strongly" mandated by member states to prepare targeted measures on Russia and impact assessment of further sanctions.

"We have been already working on this, and we are looking at broader areas that could have far-reaching consequences for the relations between the European Union and Russia," said Barroso, "So, it's a broad range of economic areas where we are in fact preparing possible targeted measures."

"We cannot yet decide exactly on the concrete measures at this moment," he added, "It depends of course on the situation."

However, not all European leaders are keen to illimitably extend sanctions against Russia, the EU's biggest neighbor and third biggest trading partner.

Martin Schulz, president of the European Parliament, warned Thursday the European leaders against "sleep-walking" into an escalating conflict.

Addressing the summit, Schulz warned "the outbreak of a new Cold War," and urged leaders to think about the outcome of possible conflict with Russia and to keep all channels of communication with Russia open.

For those EU countries having close trade and economy links with Russia, such as Latvia, Cyprus and Bulgaria, worries are mounting that further targeted measures against Russia will hurt themselves.

On Thursday, Russia barred nine U.S. politicians from entering the country as a tit-for-tat move against Washington's sanctions.

The list included U.S. Deputy National Security Advisor Caroline Atkinson, Speaker of House of Representatives John Boehner and Harry Reid, U.S. Senate majority whip.

The list came three days after the United States imposed sanctions on at least seven senior Russian officials and parliament members over Moscow's recognition of Crimea's Sunday referendum, which showed joining Russia received a landslide support from the Crimean population.

Moscow has repeatedly warned that "the use of sanctions is a double-edged sword."