Saudi air force and artillery pounded Yemeni rebel hideouts to push the rebels away from its southwestern border and stop the war spilling into its territory, a Saudi security source said on Monday.

The source said Saudi forces also detained scores of rebels during the military operation in the strategic Jabal Dukhan border area on Sunday.

The rebels said on their website on Monday that the Saudi military had widened the scope of its air offensive, carrying out repeated air strikes as well as artillery attacks on the outskirts of Saada city, the capital of their mountainous stronghold Saada province.

Saudi Arabia launched its assault on neighbouring Yemen's Shi'ite Muslim rebels -- known as the Houthis -- earlier this month after rebels staged a cross-border incursion that killed two Saudi border guards.

Global aid organisations have voiced deep concern at the escalation of the conflict in north Yemen, where the United Nations now says 175,000 people have been displaced by the fighting.

On Sunday, the Houthis said they had thwarted an attempt by the Saudi military to enter Yemen by land, inflicting "heavy losses" and forcing them to abandon a number of vehicles and weapons, according to a statement on their website.

A spokesman for the Yemeni army denied that the Saudi armed forces had entered Yemen.

"Each side is dealing with the rebels on its own territory," Colonel Askar Zaayl said. "It's not true that the Saudis are launching strikes and attacks inside Yemeni territory." – Reuters