"We condemn this killing and direct and swift reprisals are the answer," senior rebel political official Mohammed Ali al-Huthi tweeted.

The Saudi-led coalition, which has been fighting the rebels since March 2015, accuses Iran of providing them with sophisticated weapons to use against Saudi airports and oil facilities, something Tehran denies.

In September, the Yemeni rebels claimed responsibility for twin drone and missile strikes on Saudi oil facilities that briefly knocked out half the kingdom's output, sending world prices soaring.

The United States dismissed the rebel claim and alleged that it was Iran itself which orchestrated the attacks, something Tehran again denied.