The EU's unity after Russia launched its military operation in Ukraine is beginning to "crumble," according to German Economy Minister Robert Habeck on Sunday. The threat comes ahead of the EU summit, which will discuss fresh penalties against Moscow as well as a possible oil embargo.

“After Russia's attack on Ukraine, we saw what can happen when Europe stands united. With a view to the summit tomorrow, let's hope it continues like this. But it is already starting to crumble and crumble again," Habeck told a news conference.

The EU has struggled to get an agreement on placing an oil embargo on Russia, with several member countries expressing fears that the measure would be disastrous for their economies. Hungary, which gets the majority of its oil from Russia, has been the most vocal opponent of the embargo, equating the potential consequences to "an atomic bomb." Other landlocked countries, including Czechia and Slovakia, have expressed similar concerns about the embargo.

Earlier this week, European Commission President Ursula von der Leyen explained why the EU continues to purchase Russian oil.

“If we would completely, immediately, as of today cut off the [Russian] oil, [Russian President Vladimir] Putin might be able to take the oil that he does not sell to the EU to the world market, where the prices will increase, and sell it for more – and that would fill his war chests,” von der Leyen said in an interview with MSNBC.

According to reports, EU officials have attempted to reach a compromise solution to the sanctions impasse by launching the embargo by prohibiting Russian oil deliveries by the sea while exempting pipelines from prospective limitations. The initiative, however, appears to have failed, and the EU members will now attempt to agree on the limits during the meeting scheduled for Monday and Tuesday.

After Russia launched a military operation in Ukraine in late February, the EU placed a number of sanctions packages on it.

Following Ukraine's failure to fulfill the conditions of the Minsk agreements, initially signed in 2014, and Moscow's subsequent recognition of the Donbass republics of Donetsk and Lugansk, Russia launched its operation in Ukraine. The protocols negotiated by Germany and France were intended to grant the separatist areas special status within the Ukrainian state.

Since then, the Kremlin has demanded that Ukraine declare itself a neutral country that will never join the US-led NATO military alliance. Kiev maintains that the Russian offensive was utterly unprovoked and denies that it intended to seize the two republics by force.