Gulf Arab countries issued a travel warning for Lebanon on Wednesday, telling their citizens to avoid what is a popular tourist destination for the region after a spillover of violence from Syria.
Sectarian violence fueled by Syria's civil war has broken out in the northern Lebanese city of Tripoli and, last month, two rockets fired at southern Beirut, controlled by the Shi'ite Hezbollah militia, brought the violence deeper into Lebanon.
On Wednesday, Syrian government forces backed by Hezbollah fighters seized control of the Syrian town of Qusair, near the Lebanese border.
The six-nation Gulf Cooperation Council (GCC) told its citizens that the unstable security situation in Lebanon "makes the presence of GCC nationals there unsafe", GCC Secretary-General Abdulatif al-Zayani said in a statement, without elaborating.
Visitors from wealthy Gulf states account for the bulk of Lebanon's vital tourism income, which has been hit hard by the unrest in Syria.
The United Arab Emirates and Kuwait have already issued their own travel warnings for Lebanon. The GCC also includes Bahrain, Saudi Arabia, Qatar and Oman.
The Sunni Muslim leaders of the Gulf Arab states have long called for Syrian President Bashar al-Assad, whose ruling establishment are mostly members of an offshoot of Shi'ite Islam, to step down. Saudi Arabia and Qatar have both been arming the rebels.
Bahrain's deputy foreign minister said on Sunday that GCC states would consider taking action against Hezbollah if it continued its involvement in Syria's civil war or interfered in Gulf Arab affairs.
The Arab League and the United States have also urged Hezbollah to pull its fighters from Syria. France has said up to 4,000 Hezbollah militiamen are fighting alongside forces loyal to Assad.