BEIRUT - Activists say a deadline for a U.N.-brokered cease-fire has passed without reports of major violence, just hours after Syria promised to observe the halt in fighting.

The truce deadline was 6 a.m. Thursday.

But there were only dim hopes for an abrupt end to the bloodshed. Syria has backtracked on previous peace plans and has characterized the uprising it's facing as a terrorist plot.

The Britain-based Observatory of Human Rights, an activist group, says some shot were fired in a Damascus neighbourhood after midnight Wednesday and that an explosion went off in a car in a Damascus suburb, causing no injuries.

Syria said Wednesday that it would stop its military operations but that it has a right to defend itself against the terrorists it says are behind a year-old uprising.