BRUSSELS -- The European Union has added six Russian companies involved in the recent construction of the Kerch Strait bridge linking the mainland of southern Russia with the Crimean Peninsula to its sanctions list.

The decision, taken by EU ambassadors earlier this month, was published by the bloc’s Official Journal on July 31.

The EU has now frozen the assets of a total of 44 entities from Russia and Ukraine since Moscow's seizure of Ukraine's Crimea region in March 2014 and its support for separatists in a conflict that has killed more than 10,300 people in eastern Ukraine since April 2014.

In addition, 155 individuals from both countries are subject to EU restrictive measures.

Three of the Russian companies newly included in the EU sanctions list -- Mostotrest, Stroygazmontazh, and its subsidiary Stroygazmontazh Most – are owned by Arkady Rotenberg, a businessman close to President Vladimir Putin.

Rotenberg had previously been included in the list of individuals sanctioned by the EU.

According to the bloc, Russia's construction of the 19-kilometer Kerch Strait bridge has contributed to the destabilization of Ukraine’s territorial integrity.

The bridge was opened for cars and buses in May. It contains a four-lane highway and two lines of railway tracks that are still under construction. The $3.7 billion Russian construction project began in 2016.