LONDON — Europe’s top diplomats began huddling in Brussels on Monday to finalize sanctions on individuals leading the drive to split Crimea off from Ukraine and deliver it to Russia. The EU effort is likely to increase tensions with Moscow.

Foreign ministers from the 28 nations of the European Union say they are united in condemning Sunday’s secession vote in Crimea as illegal, invalid and worthy of a strong riposte. That response will start with travel bans and asset freezes on people who the EU believes facilitated Russia’s military incursion into the Crimean peninsula and expedited the referendum on breaking away from Ukraine.

The blacklist is likely to include several dozen officials in Crimea’s Russian-backed regional government and in Moscow itself, though President Vladimir Putin’s name is not expected to appear on the list.

[Updated, 6:25 a.m. PDT March 17: A few hours after their meeting in Brussels began, the EU foreign ministers announced that they had imposed the travel restrictions and asset freezes on 21 Crimean and Russian officials. The names were not immediately released.]

“We need to show solidarity with Ukraine, and therefore Russia leaves us no choice,” said Radoslaw Sikorski, the Polish foreign minister.

At the same time, the EU’s top diplomat, Catherine Ashton, said the door remained open for a political solution. Europe, along with the United States, has urged Russia to negotiate directly with Ukraine, but Moscow has so far refused on the grounds that the current government in Kiev illegitimately took power in a coup.

“There needs to be dialogue. There needs to be a way through this that can actually lead to the territorial integrity of Ukraine being assured and good and strong relations with Russia for Ukraine and for the European Union,” Ashton said.

She dismissed Sunday’s vote as a “so-called referendum” with no basis in international law. Western nations insist they will not recognize the outcome.

Crimean officials say that 97% of those who voted opted to unite the strategically important region with Russia, which ruled Crimea until 1954. The local parliament formally declared independence Monday and said it would apply to join Russia.

Whether the travel bans and asset freezes under discussion by the EU will hurt Moscow remains to be seen. Critics scoff at those penalties as laughable moves to prevent Russian officials from going on shopping sprees in Paris.

“These measures … will certainly make an impact on the individuals concerned,” British Foreign Secretary William Hague said. “Of course, they are partly a statement of our strong opposition to what has happened. An important element of this will be the readiness to adopt further measures.”

The EU, which has a strong trading relationship with Russia and imports large amounts of Russian gas and oil, says harsher economic sanctions will follow if Moscow does not de-escalate the situation in Crimea. The Kremlin has warned that it will respond to sanctions in kind.

henry.chu@latimes.com

Twitter: @HenryHChu