** Oil prices shot up after a Reuters source confirmed a report that the United States is preparing to announce on Monday that all buyers of Iranian oil will have to end their imports shortly, or be subject to U.S. sanctions

** Removing the sanctions exemptions would reduce oil supply from a market that is already tight because of U.S. sanctions against Iran and fellow OPEC-member Venezuela

** Hindustan Petroleum Corp Ltd shares fall over 6 pct to 250.50 rupees in its worst intraday pct fall since Nov 12

** Bharat Petroleum Corp Ltd plunges as much as 5.2 pct to 344.10 rupees, its biggest intraday fall in nearly 5 weeks

** Shares of Indian Oil Corp Ltd down as much as 4.2 pct to 149.50 rupees in worst intraday fall since April 8

** Bharat Petroleum and IOC among top pct losers on the NSE index which was down 0.76 pct by 0505 GMT