The US has ordered some of its embassy staff in Beirut to leave Lebanon because of potential threats to American facilities and personnel in the region.

The US department of state says it has ordered what it calls "non-emergency" staff and their families to leave Beirut.

It says the decision is due to an "abundance of caution" in light of tensions in the region and "potential threats to US government facilities and personnel".

It has also urged US citizens to avoid all travel to Lebanon.

When the Australian government toughened its travel warning last week, it authorised dependants of embassy staff to leave if they wished and advised travellers who fear for their safety to consider leaving.

Both governments warn that violence from Syria may spill-over without warning.