BBC: EU-Moscow row over South Stream gas pipeline
Russia has accused the European Union of imposing "creeping" economic sanctions following Bulgaria's decision to halt construction of a gas pipeline.
The South Stream pipeline, financed by Russia's state gas giant Gazprom, would ship gas to western Europe via the Balkans, thus avoiding Ukraine.
The project was initiated amid disagreements between Gazprom and Ukraine and Belarus over the pricing of Russian gas, which led to gas supplies to some parts of Europe being cut off. It took on added significance following the upheaval in Ukraine.