In an exclusive Al Jazeera interview, ex-operative says Saleh “plays with al-Qaeda in the Arabian Peninsula like chess”.
Saudi Arabia says it has shot down a Scud missile fired into the kingdom by Houthi fighters and forces allied to Ali Abdullah Saleh, the former Yemeni president.
A coalition of Arab states has been bombing the Iran-allied Houthis for more than two months in an attempt to restore President Abd-Rabbu Mansour Hadi, who has fled to Saudi Arabia.
About 2,000 people have been killed and half-a-million displaced by the fighting.
“At 2:45am on Saturday morning, the Houthi militias and ousted [president] Ali Abdullah Saleh launched a Scud missile in the direction of Khamees al-Mushait, and praise be to God, the Royal Saudi air defences blocked it with a Patriot missile,” a statement by the leadership of the joint Arab military coalition said.
The statement came just hours after Saudi Arabia said its army had repelled an offensive by Saleh forces backed by Houthis fighters on its Jizan province, which borders Yemen, according to state media.
Dozens of armed men, believed to belong to Republican Guard units loyal to Saleh, died in Friday’s attack, which the Saudi security sources said was the biggest since the conflict in Yemen began.
The Saudi armed forces said in a statement that four of their soldiers had died of injuries sustained during the attack.
“The Armed Forces repelled the offence which was aiming to penetrate the border, in an attempt to achieve … a moral victory to compensate for the casualties among the aggressors’ ranks,” the Saudi statement said.
Friday’s fighting is believed to have started when units of soldiers loyal to Saleh and Houthi fighters tried to infiltrate the border at Al Khouba.
The Houthi rebels released a video of what they say is a scud missile being fired into Saudi Arabia.
The rebels launched a number of rockets at Saudi military positions, before the Saudi army retaliated with artillery shelling and air support from Apache helicopter gunships.
Houthi reinforcements on the Yemeni side of the border were also targeted during the retaliation.
The rebel-aligned Al Masirah TV aired video purporting to show fighters moving towards Saudi watchtowers and firing rockets.
Elsewhere, the coalition on Friday carried out air strikes in the capital, Sanaa, and Ibb city, targeting positions of the Houthis and its allies.
Rebel military positions were also hit in Dhi Naem district in Bayda province and Ataq city in Shabwa province.
Earlier, there were violent clashes in the southern port city of Aden between Houthis and soldiers loyal to Hadi.
Fighting also broke out in the city of Taiz, with popular resistance committee forces battling the Houthis.
The fighters reportedly blew up a home in the city where Houthi fighters had been gathering.
The UN announced on Saturday that talks to end the conflict including the Houthis would begin in the Swiss city of Geneva on June 14.