Before attempting to take Damascus again, Saeed said the rebels must gather enough ammunition to sustain the battle, take over nearby army bases to prevent attacks from behind and increase coordination between rebel brigades.

He guessed that could take six months.

The Syrian government has not commented on the fall of Douma to rebels, whom it characterizes as terrorists backed by foreign powers seeking to destroy the country.

The chief of staff of Syria’s armed forces called on the army to continue its ‘‘holy and national task to crush the armed terrorist groups and their hideout,’’ the state news agency reported.

Gen. Abdullah Ayoub said the ‘‘conspiracy’’ against Syria would fail ‘‘thanks to the bravery of the Syrian army and the coherence of the Syrian people.’’

Activists reported clashes in a number of other parts of Syria on Thursday, including inside the Taftanaz helicopter base in the north.

In Jordan, the U.N. refugee agency said that around 1,200 people have fled across Syria’s southern border each day for the past three days, an increase reflecting fresh violence in the south. UNHCR reporting officer Danita Topcagic said many shops in the area were shut, making it hard for people to find food, and that electricity and water supplies were short.

About a half-million Syrians have sought refuge from the war in neighboring countries, and many more are displaced inside Syria.

Meanwhile, the parents of an American journalist who has been missing in Syria since he was kidnapped Nov. 22 appealed to his captors for compassion and any information about their son’s health and welfare. Thirty-nine-year-old James Foley was in the country contributing videos to Agence France-Press, which has vowed to help secure his release.

Twenty-eight journalists were killed in Syria in 2012, prompting the Committee to Protect Journalists to name Syria the most dangerous country in the world to work in last year.

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