BEIRUT – Syria retaliated Tuesday for last week’s expulsions of its diplomats from Washington and other capitals, barring or expelling a series of foreign envoys from 11 nations, including the United States.

But the government of President Bashar Assad also consented to international demands for augmented humanitarian access, agreeing to allow United Nations and other aid staffers to enter four strife-ridden provinces: Homs, Idlib, Daraa and Deir Elzour.

Human rights groups had complained about restricted access for aid, including food, medical assistance and shelter for victims of Syria’s escalating violence. Some estimates say more than 1 million Syrians are in need of help.

“Whether this is a breakthrough or not will be evident in the coming days and weeks and it will be measured not in rhetoric, not in agreements, but in action on the ground,” John Ging, operations director for the U.N. Office for the Coordination of Humanitarian Affairs, told reporters in Geneva.

Opening up a humanitarian flow to Syria is one of the major objectives of the six-point peace plan worked out by Kofi Annan, the U.N. and Arab League special envoy.

Diplomats deemed by Syria personae non gratae on Tuesday include U.S. Ambassador Robert Ford, who, like many or all of those on the unwelcome list, had already been pulled from Damascus, the Syrian capital. Other diplomats on the list came from Turkey, Canada and eight European nations: Britain, Switzerland, France, Italy, Spain, Belgium, Bulgaria and Germany.

The diplomatic moves are largely symbolic in nature, but they highlight the isolation of Damascus, especially from the West and from its neighbor, Turkey.