KIEV, June 4 - Ukraine has been forced to postpone shale gas extraction projects in eastern parts of the country due to ongoing fighting with pro-Russian rebels, Prime Minister Arseniy Yatseniuk said Tuesday.

The pro-Russian rebels made Slovyansk, a small city in the Donetsk region, their stronghold, and keep defying and fighting the government’s troops during the past two months.

Slovyansk sits on the huge shale gas deposit, known as Yuzivska, which is supposed to be developed by Royal Dutch Shell.

“It is a little difficult for our foreign investor partners to extract [shale] gas on the territory of Slovyansk,” Yatseniuk said addressing Parliament. “There is a temporary problem.”