A Saudi soldier looks through binoculars from a position in the al-Dokhan mountains, on the Saudi-Yemeni border in southwestern Saudi Arabia, on April 13, 2015
Riyadh (AFP) - Saudi Arabia said its forces on Thursday killed dozens of rebels from Yemen who launched their first major attack on the kingdom since Saudi-led air strikes began last month.
Three Saudi soldiers also died in the battle after the rebels targeted their observation posts, the defence ministry said.
"The ground troops today repelled an attack at the southern Najran border" by Shiite Huthis and allied troops loyal to Yemen's former strongman Ali Abdullah Saleh, it said in a statement carried by the official Saudi Press Agency.
"The ground troops engaged them" with support from air strikes, the ministry said.
"This led to.... the deaths of dozens of militias," the ministry said.
A Saudi-led coalition on March 26 began bombing in Yemen to halt a southern advance of the Iran-backed rebels.
The air strikes have sparked exchanges of fire along the border region, where nine Saudi soldiers and border guards have been killed in periodic incidents.
But this is the first time the military has reported a full-scale Huthi attack against the kingdom.
Coalition spokesman Brigadier General Ahmed al-Assiri has said that stopping the Huthis from threatening Yemen's neighbours was an aim of the military operations.
Saudi Arabia has reinforced the border with artillery, tanks and hilltop lookout posts to block the incursion of any Huthis from their traditional highland stronghold just over the boundary.
The rebels swept into Yemen's capital Sanaa last September from those bases and then advanced south on the port of Aden, forcing President Abedrabbo Mansour Hadi to flee to Riyadh.
The coalition took action, fearing that a regime friendly to Shiite Iran, Sunni Saudi Arabia's regional rival, could take control of all Yemen.
In early April the coalition said that more than 500 rebels had died in border clashes with the Saudi military since the air war began.
On the ground in Yemen, the Huthis and their allies are fighting Hadi loyalists.
The UN says about half of the more than 1,000 people killed in the Yemen fighting since late March were civilians.