Lebanon's prime minister on Saturday criticized a visit by an Iraqi Shiite militia leader to Lebanon's ceasefire line with Israel, saying it violated local law.

The trip by Qais al-Khazali, the founder and leader of the Asaib Ahl al-Haq militia, was organized by Lebanon's Hezbollah, a powerful armed movement that has fought against Israel.

A video of the visit began circulating on social media on Friday, showing Khazali wearing military uniform during a tour of parts of southern Lebanon.

"We declare our full readiness to stand united with the Lebanese people and the Palestinian cause in the face of the Israeli occupation," he can be heard saying in the recording.

In a statement, Lebanese Prime Minister Saad Hariri said the visit took place six days ago and was a "violation of Lebanese laws," without specifying further. He added that he had instructed authorities to investigate and "take measures to prevent any person from carrying out military activities on

Lebanese territory... and to prevent the person in the video from entering Lebanon."

Asaib Ahl al-Haq is an Iran-backed group that is one of the main components of Iraq's Hashed al-Shaabi paramilitary force.

Hezbollah has sent advisers to assist the force in their battle against the Islamic State (ISIS) group.

The Lebanese group is also fighting in neighboring Syria, and has been accused of assisting Huthi rebels in Yemen. Its regional interventions have been a source of tension in Lebanon, and were cited by Hariri when he announced last month that he was resigning. He later withdrew his resignation after talks that saw Lebanon's government issue a statement reasserting a policy of non-interference in regional

conflicts.

Israel fought against Hezbollah in Lebanon in 2006, after withdrawing from southern Lebanon in 2000.

The two countries remain technically at war and there have been occasional skirmishes on the border.