As repercussions from the deteriorating financial situation in Russia and the political tensions in Ukraine - which also led to the collapse of a planned asset swap between Gazprom and BASF - the German group's oil and gas subsidiary Wintershall sold its 15% share in South Stream Transport to its Russian partner Gazprom on Dec. 29.

Under the agreement, the purchase price - which was not quantified - reimburses the cash invested by BASF.

The other European shareholders of South Stream Transport including Italian energy giant Eni (20%) and French utility EDF (15%) also sold their shares to Gazprom.

South Stream Transport was founded to construct the offshore portion of the South Stream pipeline through the Black Sea. However, Russia has since withdrawn plans to build the pipeline.