Chief executives of Russia's Gazprom NEFT (SIBN.RS) and Italy's ENI SpA (ENI.MI) called Tuesday for speeding up the South Stream gas pipeline project, after Ukraine clinched a gas network agreement with the European Union, prompting Moscow's fury.

Chief executives of Russia's Gazprom NEFT (SIBN.RS) and Italy's ENI SpA (ENI.MI) called Tuesday for speeding up the South Stream gas pipeline project, after Ukraine clinched a gas network agreement with the European Union, prompting Moscow's fury.

"Alexei Miller and Paolo Scaroni discussed the realization of the South Stream project," which involves Russia and several south European countries, including Italy, Gazprom said in a statement.

"Considering the importance that the European Union attaches to diversifying ways of delivery from Russia, the earliest possible realization of this project takes on particular urgency," Gazprom said.

Ukraine signed an agreement Monday with the European Commission to pave the way for much-needed foreign investment in its gas pipeline network, seeking to boost the lines' capacity by 60 billion cubic meters a year.

However, this plan to overhaul Ukraine's Soviet-era network drew immediate fire from Moscow, and revived fears of a repeat of a January gas dispute which left a dozen E.U. countries without natural gas.

Analysts suggested that Moscow's ire was sparked by fear that its South Stream project would be threatened by investment in Ukrainian pipeline network.