Reports from Syria say violent clashes broke out less than two hours after the start of a nationwide cease-fire that began at midnight Friday, local time.
The deal includes the Syrian government and several rebel groups, but not certain Islamist groups. The monitoring group Syrian Observatory for Human Rights, based in Britain, said Friday that rebels violated the cease-fire by taking over territory in the province of Hama.
But a spokesman for the Jaish al-Nasr rebel group, told Reuters news service that government forces violated the deal by shelling areas in Idlib province, which borders Hama.
Russia, which backs Syrian President Bashar al-Assad, and Turkey, which supports rebel groups, have said they would guarantee the truce, which came after Turkey, Syria and Russia last week said they were ready to broker a peace deal in the six-year war.
There are dozens of groups fighting in Syria, and it was not immediately clear which of them have agreed to halt hostilities.
There have been three previous attempts to secure a nationwide cease-fire in Syria. The most recent was in September, but it lasted only a little over a week.
来自叙利亚的报道说，当地时间星期五午夜开始的全国停火不到两小时就爆发了冲突。
这项停火由叙利亚政府与几个反政府武装力量之间达成，不包括某些伊斯兰极端组织。总部设在英国的监督机构叙利亚人权瞭望台星期五说，反政府武装违反了停火协议，在哈马省夺取土地。
但是反政府武装力量（Jaish al-Nasr）的一位发言人告诉路透社说，是政府军违反协议，炮击了哈马省附近的伊德利卜省一些地区。
土耳其，叙利亚和俄罗斯上星期表示，他们已经谈判达成和平协议，结束这场历时六年的战争。支持叙利亚总统阿萨德的俄罗斯政府和支持叙利亚反叛力量的土耳其都表示，他们将保证停火的执行。
叙利亚有几十支反政府武装力量，目前还不清楚都有那些反政府武装同意停火。
叙利亚此前曾有过三次全国停火，最近一次是今年9月，但只持续了一个多星期。