LUXEMBOURG - European Union governments on Monday formally approved an embargo on Iranian oil to start on July 1, dismissing calls by Greece for possible exemptions to ease its economic problems.Europe and the United States are using the ban to intensify pressure on Iran to scale back its nuclear program, which they say is geared to developing weapons. Iran says its nuclear works are for electricity production and other peaceful purposes only."There is no change in terms of how we're going forward on July 1," EU foreign policy chief Catherine Ashton said on the sidelines of the meeting. "The sanctions that have been agreed will be implemented."Western governments are hoping sanctions will persuade Iran to curb its nuclear activity and in particular stop enriching uranium to a fissile level not far from that needed to produce material for nuclear bombs.Diplomatic efforts to resolve the decade-long standoff faltered at a round of negotiations between Iran and six world powers in Moscow this month, and Israel has renewed threats to attack Iran if it fails to rein in its nuclear work.International pressure has already inflicted damage to the Iranian economy. The International Energy Agency says its crude exports have fallen by some 40 percent this year.Europe was a major client for Iranian oil but under sanctions agreed in January EU governments have stopped signing new contracts for Iranian crude. Available data show deliveries virtually dried up in May and June.Greece has lobbied other EU governments to allow purchases under previously signed deals after July 1, or to provide Athens with credit guarantees that would help it to buy crude elsewhere. These requests have been rejected, diplomats said.Greece had pushed for a delay in the implementation of the EU ban - originally drafted in January - because it relies heavily on Iranian crude oil to meet its energy needs. Tehran has offered preferential credit terms to debt-stricken Athens.At a meeting in Luxembourg, EU foreign ministers said, however, that the embargo would go ahead as planned, although they pledged to review its implementation in the future to ensure European governments have sufficient access to crude.