Thousands of angry Iranians demonstrated on Friday to denounce Saudi Arabia's royal family and its air war on Shiite rebels in Yemen, where Tehran is accused of meddling by Riyadh.
The protests came as Iran rejected anew Saudi claims that it was interfering in Yemen by backing the Shiite Huthi rebels, and accused Riyadh of seeking to absolve itself of responsibility in the war.
"Death to the Saudi (royal) family", "Death to America", "Death to Israel", chanted demonstrators who thronged Tehran, according to footage shown on state television.
They also denounced US support for the military operations, it said.
Some protesters carried placards that read: "From Gaza to Yemen, stop killing children", and state television described the protest as "massive".
An effigy of King Salman of Saudi Arabia holding an American flag in one hand and an Israeli one in the other was also displayed at the rally.
In a statement published by Fars news agency, organisers of the protest criticised Riyadh, branding it "the capital that fosters radicalism and terrorism".
They also denounced the Saudi royal family, which they described as "the most prominent manifestation of American Islam and the regime that depends the most on the Great Satan", referring to United States.
Rallies were also organised in other major cities, according to media reports.
In Zanjan in northwest Iran, the crowd chanted against "the crimes of the murderous Saudi regime", while the slogan in the southern city of Bandar Abbas was "the world must know that Yemen is not alone".
Tensions between Sunni-dominated Saudi Arabia and Shiite Iran have soared following the launch in March of a Riyadh-led aerial campaign against the Huthi rebels.
The June 2013 election of moderate cleric Hassan Rouhani as Iranian president led to a timid but only brief rapprochement between the two countries.
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- Regional foes -
The regional foes have long vied for influence in the Middle East, including in the conflicts in Syria and Iraq and in confessionally mixed nations such as Lebanon and Bahrain.
In southern Iran, meanwhile, the secretary of the Supreme National Security Council, Admiral Ali Shamkhani, said in a speech that the Saudi monarchy would meet a brutal end.
"The path that the ruling family in Saudi Arabia has taken is the same as the one that Saddam trod," it said in reference to executed Iraqi dictator Saddam Hussein.
Riyadh's new Foreign Minister Adel al-Jubeir on Thursday criticised what he called Iran's "negative" role in the Yemen conflict, and repeated claims Tehran was arming and funding anti-government forces.
Iran's foreign ministry spokeswoman Marzieh Afkham dismissed the Saudi accusations.
Saudi allegations that Iran was arming the Huthis "were nothing but efforts to put the blame on others based on repeated and unfounded analysis," she said, according to official IRNA news agency.
Iran has repeatedly denied sending weapons to the Huthis.
The Saudi-led coalition has been conducting air strikes on Yemen rebel positions since March 26, and also imposed an air and sea blockade on the impoverished Arabian Peninsula country.
The UN says the conflict has killed more than 1,400 people and wounded over 6,000, amid growing concerns over a mounting humanitarian crisis.
Riyadh proposed a five-day humanitarian ceasefire on Thursday, but later warned the Huthis had crossed a "red line" by targeting southern Saudi Arabia with cross-border shelling.
Meanwhile the Iranian Red Crescent said it would dispatch Saturday a boat carrying 2,500 tonnes of humanitarian aid to Yemen.
In late April, the Saudi air force prevented an Iranian plane, which Tehran said carried aid, from landing in Sanaa.