RIYADH, Saudi Arabia - Saudi Arabian forces have taken control of a mountain straddling the border with Yemen and cleared it of Shiite rebels, in five days of fighting that saw three soldiers killed and 15 wounded, the assistant defense minister said on Sunday.

Prince Khaled bin Sultan said another four soldiers were missing and that Saudi troops were still dealing with rebel infiltrators in other spots along the frontier. Bin Sultan said Saudi forces had not entered northern Yemen nor commented on rebel casualties.

"We are dealing with infiltrators and gangs. All that they seized, including Dokhan mountain, are now under our control, although there is infiltration in some locations," bin Sultan was quoted as telling reporters after visiting the region.

Saudi warplanes and artillery last week bombarded a Shiite rebel stronghold in northern Yemen for three straight days, according to the rebel fighters.

The sporadic five-year conflict between Yemen's weak central government and rebels in the north of the impoverished country escalated dramatically last week when Saudi military forces began shelling and bombing rebel positions.

"All the mountain slopes inside the Saudi border have been cleared," bin Sultan was quoted as saying by the official Saudi Press Agency. "We deal only with those inside our land and we did not and will not intervene inside Yemen."

The two nations are cooperating and sharing intelligence in the fight. Officials in Saudi Arabia have been increasingly worried that extremism and instability in Yemen could spill over to their country, the world's largest oil exporter.

Publicly, Saudi officials say their military action has been limited to areas inside its own borders, targeting fighters who have crossed into its territory. But Yemeni rebels, military officials and Arab diplomats say the Saudi air and artillery strikes began to hit deep inside northern Yemen on Thursday.

Yemeni President Ali Abdullah Saleh on Saturday vowed to quash the northern rebels, known as Hawthis.

The rebels claim the needs of their communities are ignored by a Yemeni government that is increasingly allied with hard-line Sunni fundamentalists, who consider Shiites heretics.

Besides the northern rebels, Yemen's government is also confronting a separatist movement in the south and a lingering threat from al-Qaida militants.

Yemen, the ancestral homeland of Osama bin Laden, has cooperated with the U.S. in fighting terrorism but has struggled to confront Islamic extremists.