BEIRUT, July 20 (Reuters) - The Syrian Observatory for Human Rights said that rebels had killed at least 28 members of Syrian government and allied forces east of the capital Damascus on Thursday.

The Britain-based war monitor said a large number of fighters, including officers, had been killed or injured as they tried to advance into the rebel-held enclave of Eastern Ghouta. It said the death toll was likely to rise.

The Syrian military was not immediately available for comment.

(Reporting by Lisa Barrington; Editing by Gareth Jones) ((lisa.barrington@thomsonreuters.com; +961)(0)(1954456;))