The Saudi-led coalition fighting in Yemen threatened severe reprisals late Monday against rebels in the neighbouring country, after they fired a fourth ballistic missile in as many days towards Saudi territory.

Official media said Saudi Arabia intercepted a rocket fired towards the border city of Jazan late on Monday and then destroyed the missile launcher in Yemen.

The kingdom has deployed Patriot missile batteries designed to counter tactical ballistic missiles.

Air defences shot down another missile fired towards Jazan on Monday morning.

On Friday, the coalition said a ballistic missile had been intercepted and that a second missile struck a desert area east of Najran city.

Those attacks came after a local source reported that on September 13 another missile struck a desert area of the kingdom's south, causing no damage.

Three civilians, two of them from India, died on Saturday when shellfire from Yemen struck the border city of Najran.

All these attacks, as well as fighting on the ground in Yemen, came despite a seven-day ceasefire in conjunction with peace talks in Switzerland.

The talks between Yemen's government and Iran-backed Shiite Huthi rebels concluded on Sunday without a major breakthrough.

The head of the Yemeni government negotiating team, Foreign Minister Abdel Malak al-Mekhlafi, said the much-violated ceasefire would be extended for seven days after its expiry on Monday.

"The coalition command made it clear that while it is keen to deal positively with the Yemeni government's request for an extension of the truce, the continuation of the Huthi militias in their absurdity will push the command of the coalition to take harsh measures to deter such acts," the Saudi-led bloc said.

The Huthis are allied with elite troops loyal to former president Ali Abdullah Saleh.

On Sunday a spokesman for forces allied to the Huthis vowed to intensify missile attacks on Saudi targets.

Brigadier General Sharaf Luqman said "300 Saudi military and vital targets" had been chosen.

The rebels and their allies still have "about 60 to 70 missiles, including Tochka missiles", Yemeni army sources say, despite coalition claims to have neutralised their ballistic capabilities.

Saba news agency controlled by the Huthis confirmed they fired "a Qaher-1 ballistic missile" Monday evening.

Coalition warplanes and troops have been supporting anti-rebel forces in support of Yemeni President Abedrabbo Mansour Hadi.

More than 80 people, most of them soldiers and border guards, have been killed in shelling and cross-border skirmishes in the kingdom's south since coalition operations began in Yemen.