Brent oil futures prices jumped today, hitting a four-month high on rising concerns about a possible US military attack on Iran, OPEC’s fourth-largest producer with output of 3.2 million barrels per day.

“The immediate [market] concern … is the collateral damage done if Iran takes a swing at its neighbours or possibly even more tellingly, it closes the Strait of Hormuz to the 20 million barrels per day of oil that navigates it,” PVM analyst John Evans told Reuters news agency.

Brent crude futures were up $1.65, or 2.4 percent, to $70.05 a barrel as of 13:08 GMT. At its intra-day peak, Brent traded as high as $70.35 a barrel, its highest since late September. The contract is on track to rise over 15 percent in January, its biggest monthly increase in four years.