Western countries are expressing increasing concern regarding the deepening economic cooperation between Russia and Turkey after their meeting in Sochi, Russia, according to the Financial Times on Saturday, citing 6 Western officials.

As Russian President Vladimir Putin and Turkish President Recep Tayyip Erdogan met in Sochi to discuss the UN-brokered grain deal between Russia and Ukraine, the TurkStream gas pipeline, the construction of the Akkuyu nuclear power plant, payments in ruble for Russian gas deliveries, the situation in the Middle East, and more. 

Read more: Kremlin hopes grain deal will be fully implemented

The European Union, according to an EU official, is monitoring the Russian-Turkish cooperation "more and more closely," expressing concerns that Turkey is, more and more, becoming "a platform for trade with Russia."

"We are trying to make the Turks pay attention to our concerns," another EU official said, describing Turkey's relationship with Russia as "opportunistic." 

The Financial Times wrote, citing another senior western official that countries that have imposed sanctions against Russia could retaliate against Turkey by "calling on Western firms to either pull out of relationships in Turkey, or to shrink their relationships with Turkey, in light of the risk that would be created by Turkey expanding their relationship with Russia." 

Many European officials oppose such a measure: One official said that "there are very significant economic interests that would probably fight hard against such negative actions," according to the report. 

In addition, 3 officials said that there haven't been any discussions in Brussels about sanctioning Turkey for its relationship with Russia. 

The US has warned countries that it would impose "secondary sanctions" against any country that attempts to help Russia evade them.

Read more: Turkey: Joining sanctions against Russia unrealistic