The International Committee of the Red Cross (ICRC) said on Tuesday it had temporarily suspended its activities in the southern Yemeni port city of Aden after its office was raided by unidentified gunmen a day earlier.
Aden is largely lawless since it became a frontline in Yemen's conflict between supporters of the exiled, Western-backed government of President Abd-Rabbu Mansour Hadi and the northern, Iran-allied Houthi movement.
Although forces loyal to Hadi's exiled government in Saudi Arabia retook Aden from the Houthis last month, al-Qaida militants deployed in a western district of Aden on Saturday.
Yemeni security officials in Aden told Reuters about 50 Saudi forces had arrived in the port city on Tuesday to help rebuild the local police force, which has fallen apart in the last five months of fighting.
The head of ICRC's Aden operation Samer Jarjouhi said Monday's attack on the Red Cross offices was only the latest in at least 10 such incidents.
The attackers held staff at gunpoint and stole cars, cash and equipment, ICRC spokeswoman Dibeh Fakhr said in an emailed comment. The aid agency had relocated 14 international staff, Fakhr told Reuters in Geneva.
Seeking to fend off what they says is Iran's influence in Yemen, a Saudi-led coalition has been trying to defeat the Houthis with a campaign of air strikes since March. At least 4,300 people have died so far and Yemen has been plunged into a humanitarian crisis as the state has collapsed.
The Houthis say they are fighting a corrupt government in league with al-Qaida.
One of the few aid agencies still operating in Aden and Yemen as a whole, the ICRC has played a key role in providing medical supplies and treatment to stricken residents.
Police and government army units have mostly disappeared from Aden since fighting erupted on its streets in March. Police stations are deserted, residents say.
Yemeni security officials told Reuters that about 50 Saudi forces had arrived in Aden to train and rebuild local forces.
The pan-Arab daily Asharq al-Awsat quoted a senior Yemeni military source as saying that "Saudi special forces" had arrived in Aden to help maintain peace in the city and the surrounding areas where the Houthis had been pushed back.
UAE forces are also on the ground in Aden. On Sunday, the UAE government said their forces had freed a British hostage from al-Qaida militants who was abducted in Feb. 2014.
Plagued by chronic instability even before the latest civil war, Yemen is home to an active branch of al-Qaida and a new offshoot of Islamic State.