Syria has agreed to allow the United Nations and international agencies to expand humanitarian operations in the country, where at least 1 million people need urgent assistance after 15 months of conflict, a senior UN aid official said yesterday.

The UN is to open field offices in four violence-plagued provinces - Deraa, Deir al-Zor, Homs and Idlib - and Syrian officials have pledged to accelerate the granting of visas for aid workers and customs clearance for relief goods.

"This agreement was secured in Damascus with the government there, in writing," said John Ging, who chaired the closed-door Syrian Humanitarian Forum in Geneva.

"Freedom of movement, unimpeded access for humanitarian action within Syria, is what it's all about now. The good faith of the government will be tested on this issue today, tomorrow and every day," he said.

At least 500,000 Syrians are internally displaced in their country and many have lost their homes, according to the Syrian Red Crescent. More than 78,000 Syrians have fled to Iraq, Jordan, Lebanon and Turkey.

The UN hosted the one-day Syrian Humanitarian Forum, the third in a series, to try to expand access to hungry, sick or wounded civilians in a country reeling from an uprising against President Bashar al-Assad.

Under the agreement, procedures are to be streamlined for giving visas to aid workers from nine UN agencies and seven international non-governmental organizations, Ging said.

Advance teams are going to the four provinces this week.

Also yesterday, the Syrian government banned 17 Western diplomats.

The declaration that ambassadors from the United States, Canada, Turkey and several European countries were unwelcome was retaliation, Syria's Foreign Ministry said, for the expulsion of Syrian envoys from their capitals last week, following the massacre of more than 100 civilians at Houla.