That happened, the people said, after Bloomberg tested its computer system at an embargo procedure known as a "lockup" and found a flaw that could allow reporters to deliver data before the end of the embargo period.

WSJ: U.S. Probed Media Firms on Data Reporting

"It's going to be an irritant and, to put it simply, the embargo will stay for a longer period, " said the administrator.

BBC: Portsmouth suffer fresh setback after HMRC appeal

European officials say an embargo would either contain a grace period to leave time for refiners to find replacements for Iranian oil or make exceptions for existing long-term supply deals.

WSJ: Oil Market's Iran Fears Might Be Overdone