Iran's foreign ministry has condemned the Saudi-led air strikes in Yemen against the Shi'ite Houthi group, calling it a "dangerous step" that will worsen the crisis.
Saudi Arabia and allies including UAE, Bahrain, Kuwait, Qatar, Jordan, Morocco and Sudan launched aerial bombings against Houthi positions in the Yemeni capital Sana'a to "defend the legitimate government" of President Abdrabbuh Mansour Hadi. Government forces said they recaptured Aden airport after violent clashes with Iran-backed Houthi fighters.
Iranian state media called the military operation a "US-backed aggression" and demanded a halt to all Saudi-led action in the country. It said the raids will hinder reaching a peaceful solution in Yemen. "The attack contradicts the sovereignty of Yemen," said the foreign ministry.
The US had set up a "joint planning cell" with Saudi Arabia to provide logistical and intelligence support, according to a spokeswoman for the National Security Council.
A senior leader of the Houthi movement warned the air strikes would trigger a "wide war" in the region.
"The Yemeni people are a free people and they will confront the aggressors. I will remind you that the Saudi government and the Gulf governments will regret this aggression," Mohammed al-Bukhaiti, a member of the Houthis Ansarullah politburo, told Al Jazeera.
The Houthis, backed by Iran, have been advancing south from their base in the Yemeni capital for a week, taking an important military base to the north of the city on Wednesday (25 March).
The advance has prompted Saudi Arabia to mass troops on its porous border, with 100 fighter jets, 150,000 troops and navy units deployed in the military effort.
The Royal Saudi Air Force were also in control of Yemen's airspace.
It has also prompted scenes of chaos in Aden, residents said Wednesday, as diplomatic missions fled and residents of the largely Sunni city prepared for a Houthi invasion.
The Houthis have spread fast from their traditional tribesland in northern Yemen, taking Sana'a in January this year.