Saudi Arabia has declared a missile attack on Riyadh by Iran-backed rebels an 'act of war' and has accused Tehran of a 'blatant act of military aggression'.

Tensions have been rising between Sunni-ruled Saudi Arabia and predominantly Shiite Iran, which are locked in conflicts across the Middle East, from Yemen and Syria to Qatar and Lebanon.

The crisis escalated on Saturday when the kingdom intercepted and destroyed a ballistic missile near Riyadh's international airport.

Saudi border guards keep watch along the border with Yemen in the al-Khubah area in the southern Jizan province

The rocket had been launched from conflict-torn Yemen, in an escalation of the Saudi's war against Huthi rebels, backed by Iran.

The missile attack was the first aimed by the Shiite rebels at the heart of the Saudi capital, underscoring the growing threat posed by the raging conflict in Yemen.

Today, Saudi Foreign Minister Adel al-Jubeir also warned Tehran: 'Iranian interventions in the region are detrimental to the security of neighbouring countries and affect international peace and security.

'We will not allow any infringement on our national security.'

Iran's Foreign Minister Mohammad Javad Zarif issued dismissive tweets over the kingdom of Saudi Arabia in response.

He wrote: 'KSA bombs Yemen to smithereens, killing 1000s of innocents including babies, spreads cholera and famine, but of course blames Iran.

Today, Saudi Foreign Minister Adel al-Jubeir (pictured) also warned Tehran will 'not allow any infringement on national security'

'KSA is engaged in wars of aggression, regional bullying, destabilising behaviour & risky provocations. It blames Iran for the consequences.'

Saudi forces on Saturday intercepted and destroyed the ballistic missile near Riyadh's international airport after it was reportedly fired by Shiite Huthi rebels from Yemen.

It was the first attempted missile strike by the rebels to reach Riyadh and threaten air traffic, underscoring the growing threat posed by the conflict on Saudi Arabia's southern border.

Today the coalition sealed off air, sea and land borders in Yemen where it has been battling rebels in support of President Abedrabbo Mansour Hadi's internationally recognised government since 2015.

An Iranian foreign ministry statement quoted spokesman Bahram Ghassemi as saying the accusations by the coalition were 'unjust, irresponsible, destructive and provocative'.

Ghassemi said the missile was fired by the Huthis in response 'to war crimes and several years of aggression by the Saudis'.

The crisis between Saudi Arabia and Iran escalated on Saturday when the kingdom intercepted and destroyed a ballistic missile near Riyadh's international airport (pictured)

The missile attack, he said, was 'an independent action in response to this aggression,' and Iran had nothing to do with it.

Critics have accused the coalition of not doing enough to prevent civilian deaths in its air war in Yemen, where more than 8,650 people have been killed since the intervention began.

Repeated attempts to bring about a negotiated settlement to the conflict have failed, including a series of UN-backed peace talks.

Saudi Arabia has blamed the Huthis for the failed efforts, and on Monday offered rewards totalling $440 million for information on 40 senior officials among the rebels.

Topping the list, with a $30-million reward for tips leading to his capture, was the group's leader Abdulmalik al-Huthi.

The Huthis, allied with Yemen's ex-president Ali Abdullah Saleh in the conflict, have captured the capital Sanaa, forcing Hadi's government to operate from the southern city of Aden.