A close senior political ally of German Chancellor Angela Merkel told Reuters on Friday that the European Union and the United States should consider banning all Russian ships that originate from the Sea of Avoz from entering EU and US ports until last Sunday's Kerch Strait crisis is resolved.

Christian Democratic Union (CDU) candidate for the party chair Annegret Kramp-Karrenbauer (pictured right)

German conservative Annegret Kramp-Karrenbauer, who is said to be most likely to succeed Merkel as leader of the Christian Democratic Union (CDU) party, told Reuters:

One answer might be, for example, to stop Russian ships coming from the region - from the Sea of ​​Azov - from entering European or U.S. ports until this situation with Ukraine is resolved.

And turning her attention to US sanctions targeting Russia and Germany's less than eager willingness to go along, Reuters reports further:

Turning to tensions with the United States, Kramp-Karrenbauer said top executives from German carmakers Volkswagen, BMW and Daimler should be careful not to undermine the EU’s trade position when they meet U.S. officials at the White House next week.

Though this is the first time such a threat has been floated by a political official in a lead EU country, it comes amidst a series of tit-for-tat measures following the Russian Navy seizing three Ukrainian ships and 24 sailors in the Black Sea last Sunday as the crew stands accused of “dangerous maneuvers” in Russian territorial water.

Following the incident President Petro Poroshenko said during a Tuesday Ukrainian television interview that the threat of "full-scale war" with Russia could be imminent, in what appeared a telegraphed and sensationalized attempt to grab the attention of NATO.

Poroshenko condemned what he described as a rapidly increased Russian military presence on the border with Ukraine, saying, "The number of [Russian] tanks at bases located along our border has tripled," according to the AFP.

On Wednesday he also signed legislation introducing martial law across ten Ukrainian provinces, and on Friday a new anti-Russian travel ban was announced for Russian men ages 16-60.

Moscow for its part has announced a series of defensive measures focused on the Crimean as tensions soar, including deploying more of its advanced S-400 surface-to-air missile systems to the peninsula and increasing its naval presence on the Black Sea.

Meanwhile Britain has dispatched a reconnaissance vessel to the Black Sea amid calls from UK defense officials to beef up its presence in and around Ukraine through warships and increased troop deployment.