SIMFEROPOL, Ukraine >> Ignoring pressure and objections from the West and from Ukraine’s fledgling national government, the pro-Russian authorities in Crimea pressed ahead Thursday with plans to break away from Ukraine and become part of Russia instead.

The developments came as leaders of the European Union held emergency talks in Brussels to reinforce support for the national government in Kiev, and to look for ways to press President Vladimir Putin of Russia to de-escalate the crisis in Ukraine, one of the most serious East-West confrontations since the Cold War.

Earlier, the 28-nation bloc announced measures to freeze the assets of the Russian-backed former president of Ukraine, Viktor Yanukovych, and of 17 of his closest aides and family members, holding them responsible for the embezzlement of state funds.

The Official Journal of the European Union, which lists the body’s decisions, said that “all funds and economic resources belonging to, owned, held or controlled by” Yanukovych, two of his sons and his associates on EU soil “shall be frozen.” Yanukovych fled to Russia as his foes moved to depose him in Ukraine.

Among the targets of the measures are former ministers of the interior and justice, the former prosecutor general, the former head of the security services, and former Prime Minister Mykola Azarov and his son.

The pro-Moscow authorities in Crimea, and the Kremlin itself, seemed to be undeterred, moving to tighten their grip on the Crimean Peninsula, where Ukrainian military installations are under a tight blockade by Russian forces.

The Crimean parliament said Thursday that a referendum would be held on March 16, two weeks earlier than initially planned, offering citizens of the region a choice of remaining part of Ukraine or joining the Russian Federation. The referendum – rejected by Ukraine – had originally been scheduled for March 30.

Crimean lawmakers also said they had approved a resolution seeking membership in the Russian Federation.

Officials said the resolution was a required legal precursor to calling a referendum. The impact of the move and the consequences of its timing, however, appeared unclear. European and Ukrainian authorities rejected the latest moves as violating the Ukrainian Constitution and representing the views only of pro-Russian lawmakers in Crimea.

“My position is that this referendum is unconstitutional,” the Ukrainian economy minister, Pavlo Sheremeta, told reporters in Kiev. And a senior European official said Ukraine’s Constitution required any change of territorial sovereignty to be put to a vote of all Ukrainians, not just those in one region.

In Moscow, Dmitri S. Peskov, a spokesman for Putin, was quoted by Russian news agencies as saying that the Kremlin had been informed of the developments in Crimea but had no further comment. Prime Minister Dmitry Medvedev said Russia would simplify the procedures for people who have lived in Russia or the former Soviet Union to secure Russian citizenship.

The quick-moving developments came a day after the United States tried and failed to arrange the first diplomatic meeting in Paris between representatives of the Kremlin and the new leadership in Ukraine. U.S. Secretary of State John Kerry and his Russian counterpart, Sergey V. Lavrov, said Wednesday that more discussions would be held in the days ahead.

Early Thursday, however, Lavrov said Western moves to involve international bodies such as the Organization for Security and Cooperation in Europe and the NATO-Russia Council were counterproductive.

“I want to very briefly say that we had a meeting with U.S. Secretary of State John Kerry on the situation in Ukraine in relation to the actions that our partners are trying to take via the OSCE, the NATO-Russia Council and other international organizations – action that does not help create an atmosphere for dialogue and constructive cooperation,” Lavrov said in a statement issued by the Russian Foreign Ministry on Thursday.

The statement added that the “threats and ultimatums” made it difficult to reach “honest arrangements” that would help stabilize the situation in Ukraine, apparently referring to blistering statements by Kerry and other officials.

European leaders converged on Brussels for a meeting Thursday that was also to be attended by Ukraine’s interim prime minister, Arseniy P. Yatsenyuk. The meeting followed promises of some $15 billion in financial and economic support from the European Union for the new government in Ukraine.