'Our objective is to make sure that we don't enhance any price increase that could result from the attack, if there is one,' Khelil told Reuters in Rome during a week-long visit to Italy. 'We don't want to make a decision just before that happens,' he added.

oil prices have slumped by about 20 percent since the September 11 attacks on the United States.

Opec's oil basket price has now spent eight consecutive days below the cartel's $22-$28 per barrel target range.

'Military action could have a big impact on prices. Prices will definitely increase – but we don't know how much they will increase,' Khelil said.

'Our objective is to stabilize prices,' he added.

oil markets needed time to absorb Opec's three output cuts so far this year, the last of which took effect on September 1, which had already dealt with oversupply, Khelil said.