Houthis have increased missile attacks against Saudi Arabia, which has led coalition against them since 2015
Houthi rebels in Yemen fired a "projectile" at the southwestern Saudi province of Jizan, killing three civilians on Saturday, the Saudi-led coalition opposed to the Houthis said.
"The terrorist Iranian-Houthi militia has targeted civilians with a projectile" killing three in Jazan, coalition spokesman Colonel Turki al-Maliki said.
Malki, quoted by the official Saudi Press Agency, did not identify the type of "projectile" but said it was "launched deliberately to target civilians" and warned of retaliation.
"The Joint Forces Command of the coalition will strike with an iron fist all those who threaten the safety and security of Saudi nationals, residents and critical capabilities," he said.
Last month, the rebels fired a salvo of missiles at the capital Riyadh, saying they were aimed at economic targets.
— The Daily Caller (@DailyCaller) June 8, 2018
The Iran-backed Houthis have ramped up missile attacks against neighbouring Saudi Arabia, which leads a military coalition that has fought the rebels since 2015.
On Tuesday, Saudi air defences intercepted a ballistic missile that targeted the western city of Yanbu after being fired from rebel-held territory in Yemen.
The attack came as coalition-backed Yemeni forces advanced on the rebel-held Red Sea port of Hudaida, the main conduit for humanitarian supplies into a country teetering on the brink of famine.
Saudi sources said the UN special envoy for Yemen, Martin Griffiths, was in the Houthi-controlled capital, Sanaa, to discuss the possibility of international control of the port, according to the Guardian.
Saudi accuses, Iran denies
In late May, air defences intercepted Houthi missiles over the southern cities of Najran and Jizan and there were no casualties.
Riyadh accuses its regional rival Tehran of supplying the Houthis with ballistic missiles, a charge Iran denies.
Saudi Arabia, the United Arab Emirates and other Arab allies intervened in Yemen in March 2015 in an attempt to push back the rebels and restore the internationally recognised government to power after the Houthis ousted it from large areas of the country including Sanaa.
Almost 10,000 people have been killed since the alliance launched its intervention, contributing to what the UN has called the world's worst humanitarian crisis.