Houthi missile strike hits Saudi desalination plant
He warned that the coalition will take "firm measures, urgent and timely, to deter this terrorist militia", Maliki said.
"The terrorist elements responsible for planning and executing these acts... will be held responsible."
Earlier, the Houthis said they hit a power station in the southern province of Jizan, through the movement’s Al Masirah TV station.
Brigadier Yahya Sari, spokesman for the Houthis, said the missile strike off Najran, by the grace of God, struck "large gatherings of the Saudi enemy".
Dozens of dead and wounded mercenaries were seen being transported by cars after the strike, he added, noting the attack, that was filmed, will be published shortly.
The US said it was aware of a missile strike in Saudi Arabia.
"We are closely monitoring the situation and continuing to consult with our partners and allies," White House spokeswoman Sarah Sanders said, noting US President Donald Trump was briefed about the strike.
Pentagon spokeswoman Navy Commander Rebecca Rebarich said such attacks were "a significant cause for concern and (put)innocent lives at risk".
The Houthis have intensified attacks in the past few weeks against the kingdom, which launched military operations in Yemen in 2015 as part of a coalition to push back against the rebels.
On 12 June, a missile fired at Abha airport in southwestern Saudi Arabia wounded dozens of civilians - in an attack claimed by the Houthis.
The rebels also claimed responsibility for a series of drone strikes on Saudi Arabia, including an attack that damaged two oil pipeline pumping stations on 14 May.
Saudi Arabia accuses its regional arch-rival Iran of being behind the attacks, either directly or through supporting the Houthi rebels.
However, the rebel group has consistently denied those claims alleging the they are "independent in our decisions and ... we are not subordinated to anyone", Mohammed Ali al-Houthi, the president of the rebel's Supreme Revolutionary Committee said.
The Houthis instead say the attacks are motivated by Saudi Arabia's failure to comply with peace initiatives in Yemen.
On Wednesday, Arab parliamentarians gathered in Cairo and urged the UN to list Yemen's Houthi rebel movement as a "terrorist organisation" while accusing it of attacks on Saudi Arabia.
Though the rebels have intensified aggression towards the kingdom, Thursday's strike would mark the second time such time a cruise missile was used by the rebels.
If confirmed that would represent a major leap in the rebels' military capability, which has so far been limited to drone strikes on the kingdom.
Increased death toll
Meanwhile, a database tracking violence said on Wednesday that Yemen's civil war has killed at least 91,600 people so far, presenting a new estimate after completing reporting for the first months of fighting in 2015.
The Armed Conflict Location & Event Data Project, or ACLED, said that in 2015, about 17,100 people were reported killed — the second-most lethal year after 2018, which was the deadliest one on record.
ACLED said 11,900 people were killed this year, compared to 30,800 in 2018.
The group said the Saudi-led coalition and its allies were responsible for more than 8,000 of about 11,700 deaths resulting from the direct targeting of civilians, while the Houthis and their allies were responsible for the rest.
The group said it recorded over 18,400 killed in the southwestern province of Taiz since 2015, placing Taiz as the most violent province in Yemen, largely due to a four-year siege by the Houthis, the group said.
Hodeida and Jawf followed Taiz as the next most violent provinces in Yemen, with almost 10,000 in total combat fatalities, reported in each region since 2015, according the group.
Civilians have borne the brunt of the conflict, which has created what the United Nations says is the world's worst humanitarian crisis.
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