Cairo: Yemen’s Iran-allied Al Houthi militants said on Wednesday they had released two sons of their one-time ally and former president Ali Abdullah Saleh after months in detention.

Salah and Madeen Saleh were released in the rebel-held capital Sana’a under a pardon from Mahdi Al Mashat, the head of Al Houthis’ so-called Supreme Political Council, according to the militant-controlled news agency, citing a security source. The agency did not give further details.

Their release came after mediation from the Sultanate of Oman, Yemeni media said.

Salah and Madeen were later Wednesday transported aboard a special plane from Sana’a to Amman, Yemeni news portal Adan Al Ghad reported.

The site said that the younger Salehs had been freed after they promised not to engage in any political or military activity against Al Houthis, who staged a coup against Yemen’s internationally recognised government in late 2014.

Al Houthis detained Saleh’s two sons last December after their father broke an alliance with the militia fighting the legitimate government. That month, Al Houthis killed Saleh.

Yemen has been wracked by war since Al Houthis overran Sana’a and forced the government to leave the capital in early 2015.

In March 2015, an Arab coalition led by Saudi Arabia and the UAE, intervened in Yemen at a request from the government against Al Houthis after the militants advanced on the southern city of Aden, the temporary capital of the country after their takeover of Sana’a.

In recent weeks, the government forces, supported by the coalition air power, have stepped up their campaign against Al Houthis after the extremists last month undermined a UN attempt to revive Yemen’s long — stalled peace process in indirect talks in Geneva.

The multi-front campaign has since resulted in military and territorial setbacks for Al Houthis.

A number of militiamen were killed in the central province of Al Bayda after the army artillery shelled a militant military vehicle, the Dubai-based television Al Arabia reported Wednesday.

The vehicle was hit east of Al Badya where it was on its way to reinforce the extremists there, according to Al Arabiya.