BRUSSELS - EU foreign ministers were preparing the "strongest possible signal" to Russia on Monday by making it pay a price in sanctions for backing a Crimea vote for independence from Ukraine.
At the same time they reiterated the need for a diplomatic solution, urging Moscow to begin talks on solving the worst crisis in Europe since the end of the Cold War.
"We are trying to send the strongest possible signals to Russia, a signal trying to ensure that they understand the seriousness of the situation," said the European Union's top diplomat Catherine Ashton on joining talks with the ministers.
"I call upon Russia yet again to meet with the Ukrainian leaders and to start dialogue with them and to try to move to de-escalation as quickly as possible," Ashton added.
The 28 foreign ministers met after a referendum Sunday showed an overwhelming majority in Crimea in favour of joining Russia, a vote they decried as illegal, improper and in violation of Moscow's own international commitments to preserve the territorial integrity of Ukraine.
British Foreign Secretary William Hague said that after an initial set of sanctions decided last month suspending visa and economic talks, the EU will "now move to a further stage, with travel bans and asset freezes against individuals."
Sanctions would be "a very strong statement" about the unacceptability of Russia's actions in the 21st century, Hague said.
"We are also prepared to move to further measures," if Moscow shows no sign of reversing course, he said, urging Moscow to take the diplomatic route and ruling out any consideration of military action.
"We're not looking at military options here, this is not about a Crimean war," he said.
French Foreign Minister Laurent Fabius said the EU needed to "show a great deal of firmness but also to try to find a dialogue and avoid escalation."
- Crimea to apply to join Russia -
In Crimea, the pro-Moscow assembly declared independence from Ukraine and formally applied to join Russia after 96.6 per cent of voters on the mostly Russian-speaking peninsula chose to secede.
US President Barack Obama phoned his Russian counterpart Vladimir Putin to say the vote "under duress of Russian military intervention, would never be recognised by the United States and the international community."
Obama threatened "additional costs" after Washington last week imposed visa bans targeting those blamed for threatening the sovereignty or territorial integrity of Ukraine.
The EU measures under discussion in Brussels are likely to target around 25 politically significant individuals - Russians and pro-Russian Ukrainians, EU diplomatic sources said Friday.
This list will not include members of the Russian government since that would make efforts to find a way out of the crisis even more difficult, the sources said.
"There will likely be members of parliament, members of the security forces ... and a senior defence ministry official but not the minister himself," one of the sources said.
Before Monday's meeting, the EU foreign ministers met their Ukraine counterpart Andriy Deschytsya who will also hold talks with NATO head Anders Fogh Rasmussen.
Europe's leaders agreed last week to consider economic sanctions - likely to be much more damaging - against Russia if it does not change tack and seek a diplomatic solution.
Leaders of the bloc are to hold a summit focused on the Ukraine crisis on Thursday and Friday as the EU tries to salvage the keystone of its Eastern Partnership policy.
They are expected to sign the political chapters of an EU association accord which pro-Russia president Viktor Yanukovych ditched in November, sparking the Ukraine protests which led to his ouster.
Brussels has already offered to implement the provisions of an accompanying trade accord and offered up to 11 billion euros ($15 billion) in aid to help steady Ukraine's faltering economy.