Lebanese state media said US envoy Tom Barrack cut short a visit to the south on Wednesday, amid protests in two planned stops against US pressure to disarm Hezbollah.
The official National News Agency (NNA) reported that Barrack arrived by helicopter at a Lebanese army barracks in Marjeyoun near the border, with soldiers deploying in the area.
The news agency later reported that the envoy had cancelled planned stops in nearby Khiam, which was pummeled by Israel during its latest hostilities with Hezbollah, and in the coastal city of Tyre.
A spokesperson told AFP the US embassy did not comment on officials' schedules for security reasons.
An AFP correspondent in Khiam saw a group of residents, some waving Hezbollah flags or holding pictures of fighters killed in the conflict, demonstrating against Barrack.
Some were standing on a Star of David that had been drawn on the road in blue, near the words in Arabic "America is the great Satan", and "Barak is animal" written in English.
The last was a reference to comments by the US envoy at a Beirut press conference on Tuesday which sparked an outcry in Lebanon.
Barrack told journalists to "act civilized", adding: "The moment that this starts becoming chaotic, like animalistic, we're gone."
Bilal Kashmar, an official from the southern municipalities union, said dozens of people had demonstrated in Tyre on Wednesday against Barrack's expected visit and Washington's "biased policies".
Under heavy US pressure and amid fears of expanded Israeli military action, Lebanon's government tasked the army this month with drawing up a plan to disarm Hezbollah by year end.
The Iran-backed group, which enjoys strong support in the south, was left badly weakened by more than a year of hostilities including two months of open war with Israel that largely ended with a November ceasefire.
Fellow US envoy Morgan Ortagus said in Beirut on Tuesday that the Lebanese government needed to implement its decision to disarm Hezbollah, adding that Israel would respond in kind.
Hezbollah insists that Israel must complete its withdrawal from Lebanon and halt its continuing strikes before the future of the group's weapons can be discussed.
