A Saudi policeman was shot dead on Friday during a raid in which three people were arrested and flags of the Islamic State group were found, the interior ministry said.

The killing came with the Gulf region on alert against attacks by IS, which has been blamed for killing other Saudi policemen and has claimed three deadly mosque bombings in the kingdom and Kuwait.

Interior ministers of the Gulf states Friday vowed to take a united stand against a string of deadly bombings targeting Shiite mosques claimed by the Islamic State jihadist group.

Holding an emergency meeting in Kuwait, the scene of the latest suicide attack that killed 26 people last Friday, the ministers of the Gulf Cooperation Council (GCC) states stressed the attacks are a threat to the stability of the region.

Saudi tycoon Prince Alwaleed bin Talal on Wednesday promised his entire $32 billion (28.8 billion euro) fortune to charitable projects in coming years, in one of the biggest ever such pledges.

The pledge is "maybe... the first such big announcement" of its kind in the region, and is modeled on a charity established by Microsoft founder Bill Gates in the United States, the prince told reporters.

Saudi-led coalition air strikes on a rebel stronghold in Yemen have destroyed houses, markets and a school, killing dozens of people in what could amount to war crimes, Human Rights Watch said Tuesday.

The U.S.-based rights group said it had investigated the attacks on the northern city of Saada and found that at least 59 people had died in a month, from April 6 to May 11, including 14 women and 35 children.

U.N. Secretary-General Ban Ki-moon on Monday called for a full investigation after Saudi coalition air strikes hit a U.N. compound in Yemen.

A guard was injured when the office of the U.N. Development Program in the southern city of Aden was hit on Sunday, causing serious damage, said U.N. spokesman Farhan Haq.

Commercial cargo ships carrying food, fuel and other vital supplies must be allowed to reach ports in Yemen which is threatened by famine, the U.N. Security Council said Thursday.

The Saudi-led coalition battling Shiite Huthi rebels in Yemen has imposed maritime controls that U.N. diplomats have described as a blockade preventing imports from reaching Yemen.

Three Saudi soldiers and an Emirati have been killed on Saudi Arabia's border with Yemen, where Riyadh is a leading a bombing campaign against Iran-backed rebels, state media said Thursday.

Two Saudi troops were killed at sunset Wednesday when a rocket landed in the Jizan region, the Saudi-led coalition said in a statement carried by the SPA state news agency.

The U.N. envoy for Yemen on Wednesday urged warring sides to agree to a ceasefire as fighting pushed the poor Arab country closer to famine and deeper into humanitarian crisis.

Mauritanian diplomat Ismail Ould Cheikh Ahmed said a ceasefire was a priority after reporting to the Security Council on his failed peace talks in Geneva last week.

France's $3 billion Saudi-funded deal to provide military supplies to Lebanon has not been canceled, the Saudi foreign minister said Wednesday, despite the delays.

"There is an agreement... there is no blockage. Everything is proceeding normally," said Saudi Foreign Minister Adel al-Jubeir during a visit to Paris. 

France said Wednesday it would look into building two nuclear reactors in Saudi Arabia as part of a multi-billion-euro package of deals, days before the deadline of nuclear talks with the kingdom's rival, Iran.

A feasibility study will be carried out to build two European Pressurized Reactors in Saudi Arabia, French Foreign Minister Laurent Fabius announced after a meeting with Saudi Defense Minister Prince Mohamed bin Salman in Paris.