The Saudi-led coalition in Yemen said on Saturday that it had launched air strikes in support of pro-government forces battling a Houthi rebel advance on the northern city of Marib.
The move began after a drone strike set a Riyadh oil refinery ablaze on Friday, in an attack claimed by the Houthis, and condemned internationally.
The EU and Russia on Saturday joined the US in condemning the attack and calling for an end to strikes on civilians and civilian infrastructure.
The Iran-backed militia has been fighting through the rough, mountainous terrain of the Yemeni government's last northern stronghold, but has faced heavy air strikes from Saudi Arabia's air force.
The air strikes were intended to "thwart the Houthi militia's attempt to advance towards Marib at Al Kasrah", the official Saudi Press Agency (SPA) reported.
Al Kasrah is one of the lines of defence to the north-west of Marib, the capital of an oil-rich region.
The coalition, which entered the Yemen conflict in 2015 to defend the government, said it had succeeded in destroying Houthi military equipment, including tanks, and inflicting "heavy losses".
Houthi-controlled Al Masirah television reported 38 air strikes across Marib, while a government official told AFP that the coalition had launched at least 20 strikes.
One reason for the discrepancy could be that a single air strike can involve multiple bombing runs.
"At least 70 fighters were killed, including 22 from the government forces, and dozens were injured in clashes in the past 48 hours," a source told AFP.
"The rebels launched a violent attack, including with tanks, in Al Kasrah and the attack was thwarted with aerial support from the coalition."
The Houthis and the internationally recognised government have been locked in a power struggle since 2014, when the Iran-backed militias overran the capital Sanaa. Since last month, the rebels have been pushing to seize Marib.
Loss of the city would be a catastrophe for civilians, including at least one million displaced people sheltering in the region, many in camps in the surrounding desert.
Despite the latest rebel advance, analysts said the city may not fall any time soon, given the coalition's firepower.
The Houthis have been stepping up their cross-border attacks on Saudi Arabia despite a renewed push by the US administration of President Joe Biden to revive stalled peace talks.
Also on Saturday, the coalition said it had intercepted and destroyed a drone carrying explosives over the southern Saudi Arabian city of Khamis Mushait, SPA reported.
The coalition said it was taking "all operational measures to protect civilians and civilian infrastructure against terrorist attacks", SPA added.
Refinery attack condemned
The EU said "these aggressions must stop" in a statement on Saturday condemning the strike on the Saudi oil refinery.
"The ongoing escalation in and around Yemen is undermining the efforts of the UN special envoy, delaying the prospect of a solution to the conflict, and increasing regional instability," it said.
Russia also condemned the attack on Saturday, urging "all parties to the conflict in Yemen to strictly abide by the provisions of international humanitarian law" in a statement from the foreign ministry.
Moscow called on all sides to "immediately and completely abandon military operations that lead to the destruction of civilian infrastructure and casualties among the civilian population".
