Fierce clashes erupted on the Saudi border with Yemen, between the Houthi militants and pro-former Yemeni President Ali Abdullah Saleh forces on one side, and the Saudi army. Local sources said that the Houthi rebels and the Yemeni Republican Guard forces attacked different parts in the Saudi territory on Wednesday.

On the other hand, scores were killed and injured in ongoing clashes between Houthi militiamen and pro-government forces -- backed by Saudi-led coalition warplanes -- in Yemen’s northwestern Hajjah province near the border with Saudi Arabia.

According to a statement issued by the Yemeni army’s Fifth Brigade, clashes continued for the third day in a row in Hajjah’s Harad and Midi areas.

"At least 37 Houthis and allied fighters have been killed or injured," the statement read, noting that six army personnel had also been killed in the fighting.

A medical source in Yemen’s southern Aden province, meanwhile, said that at least five pro-government fighters had been killed -- and another 17 injured -- by an early morning missile attack.

In a related development late Tuesday, Saudi-led coalition warplanes pounded Houthi positions in Yemen’s western Hudeida province, one day after Houthi militiamen reportedly attacked a Saudi warship.

In 2014, the Houthis overran capital Sanaa and other parts of Yemen, forcing members of the country’s Saudi-backed government to temporarily flee to Riyadh.

The following year, Saudi Arabia and its Arab allies launched a major air campaign aimed at reversing Houthi military gains in Yemen and shoring up the pro-Saudi government.