The UN has expressed concern about the situation in the southern Syrian city of Deraa as a government crackdown on dissent continues.
It said a humanitarian mission had not been allowed access to the city, and a UN agency had been unable to get medical supplies to refugees.
Deraa has been cut off for the past two weeks, after troops and tanks were sent in to restore government control.
Meanwhile, the EU has announced an arms embargo on Syria.
In a statement, the bloc said it was banning the shipment to Syria of "arms and equipment that could be used for internal repression".
Thirteen "officials and associates of the Syrian regime" are banned from travelling anywhere in the 27-nation union and have had their assets in EU countries frozen.Hopes
The UN announced last week that President Bashar al-Assad had agreed to a request from the global body's Secretary-General, Ban Ki-moon, for a humanitarian mission to be sent to Deraa, where scores of protesters are reported to have been killed in recent weeks.
But UN humanitarian chief Valerie Amos told reporters on Monday: "We were expecting to go in with a mission to Deraa yesterday. That was postponed by the government."
She said no reason had been given, but added that she had been assured relief teams would be allowed to "go in later this week, which I very much hope will be possible".