Azerbaijani, Georgian, Romanian and Hungarian leaders signed a deal on Saturday on an underwater electric cable under the Black Sea to deliver green Azeri energy to Europe.

The agreement involves a 1,100-km (685-mile) electric cable of 1,000 MW under the Black Sea, from Azerbaijan to Romania, as part of wider European Union efforts to diversify energy resources away from Russia amid the Ukraine war.

"Given the current security context marked by the military aggression against Ukraine we need to cooperate better and show more solidarity to mitigate common challenges," Romanian President Klaus Iohannis told the meeting also attended by European Commission President Ursula von der Leyen.

"Our energy co-operation responds to a strategic impetus. It will enhance our energy resilience and ensure diversification of supply and transport routes. It is market driven given increased energy demand in Europe," Iohannis said.

Von der Leyen told the meeting that the EU's strategy to turn its back on Russian fossil fuels and diversify towards what she called "reliable energy partners" was working.

She said the EU was ready to provide financial support to the project pending the results of a feasibility study.

"To integrate a growing share of renewables, we need indeed stronger electricity interconnections. This is why the Black Sea energy cable between Romania, Georgia and Azerbaijan is so important," von der Leyen said.

"It will help reinforce our security of supply by bringing electricity from renewable sources to the EU via Romania and through Hungary."

Von der Leyen said the Black Sea cable could transform Georgia into an electricity hub and integrate it into the EU internal power market, while it could also help start to rebuilding Ukraine's energy system and the country's reconstruction.