KIEV, June 20 - Ukraine may begin tapping shale gas deposits in the second quarter of 2012 after contracts with major energy oil and gas companies are signed, a senior official at Naftogaz Ukrayiny said over the weekend.

Vadym Suprun, the deputy head of Naftogaz Ukrayiny, said that Exxon Mobil, ConocoPhillips and Shell are among the companies that will probably be involved in shale gas production in Ukraine.