The Israeli military says its troops have started a limited ground operation against Hezbollah militants in southern Lebanon.

The Israel Defense Forces announced at around 2 a.m. on Tuesday, local time, that "a few hours ago, the IDF began limited, localized and targeted ground raids" in southern Lebanon.

Before the IDF announcement, US State Department spokesperson Matthew Miller told reporters on Monday that the department had been informed of the ground operation by the Israeli side.

Miller said, "They have at this time, told us that those are limited operations focused on Hezbollah infrastructure near the border."

Hezbollah deputy leader Sheikh Naim Qassem earlier issued a statement, saying that the group will continue to fight against Israel, and that it is ready to meet an Israeli ground offensive.

The Israeli military has ramped up its attacks on the Shia Muslim militants after it killed their leader Hassan Nasrallah in Friday's airstrike against the group's headquarters near the Lebanese capital of Beirut.

Concerns are growing that the limited ground operation by Israel could lead to an escalation of the conflict in the Middle East.