By Stephanie Nebehay
GENEVA, July 25 (Reuters) - The United Nations has halved the number of international aid workers deployed in Syria in the past week due to the deteriorating security situation in Damascus, a U.N. source said on Wednesday.
The decision to "relocate" staff deemed non-essential for humanitarian operations was taken by U.N. security officials last Thursday, a day after an explosion killed four members of President Bashar al-Assad's inner circle in the capital.
"I believe 30 international staff are left in Syria now," the source told Reuters, speaking on condition of anonymity.
John Ging, a senior U.N. aid official, said on July 16 - two days before the bombing - that 60 expatriate staff were working in the country at the time. But Syria was refusing visas to Western aid workers, hampering U.N. aid efforts.
A U.N. official in Geneva said that critical humanitarian work would continue with the staff remaining in Syria.
"Non-essential staff have been relocated from Syria in view of the deteriorating security situation. Non-essential missions to Syria have been put on hold," said the official.
Another U.N. source said staff had gone to Amman and Beirut while waiting to see how the situation evolved.
The Syrian army turned its forces on Aleppo on Wednesday, ordering an armoured column to advance on the city and pounding rebels there with artillery and attack helicopters, opposition activists said.
The United Nations has been trying to launch a full-scale humanitarian operation in Syria after being shut out of the country for most of the 16-month-old conflict.
About 1.5 million Syrians need assistance, according to the world body whose food, medical supplies and other relief items are distributed by the Syrian Arab Red Crescent.
"We are still focusing on scaling up (operations). That is, our priorities have not changed," the U.N. official said.
The U.N. has been slow in granting its staff, who were outside of the country on leave or other travel, permission to return to Syria, a diplomat familiar with the situation said.
"It is a frequently used way to reduce the number of staff without being overt," the diplomat told Reuters.
"The bomb was really where the war was taken to Damascus. Damascenes are leaving and there is significant fighting, it changed security for the U.N.," he said.
"The U.N. wants to wait before they allow more staff to go in. They are still waiting to see whether the situation stabilises enough to be able to deliver assistance," the diplomat said. "If they can't, there is no reason to be there."
The International Committee of the Red Cross (ICRC), the main international aid agency working across the frontlines throughout the conflict, currently deploys 50 staff in Syria.
(Reporting by Stephanie Nebehay)