Lebanon's Prime Minister Tammam Salam (left) walks with former Lebanese prime minister Saad al-Hariri at the government's headquarters in Beirut on August 8, 2014. Hariri arrived back in Lebanon on Friday for the first time in three years. Picture: Georges Farah

Beirut - Former prime minister Saad al-Hariri arrived back in Lebanon on Friday for the first time in three years, a visit seen as re-asserting his leadership over the Sunni community after a deadly incursion by Islamist militants in the north-east.

With no prior announcement, Hariri arrived at the government's headquarters in Beirut, where he met Prime Minister Tammam Salam, footage broadcast by local television stations showed.

Hariri, Lebanon's most influential Sunni politician, has been in self-imposed exile between France and Saudi Arabia since 2011. He left the country after his government was toppled by a coalition including the Iranian-backed Shi'a group Hezbollah.

The Saudi-backed politician arrived in a Mercedes with blacked-out windows to the central courtyard of the Grand Serail, the government headquarters in central Beirut. He grinned widely as he walked into the Serail.

His visit follows a deadly incursion by Islamist militants who crossed from Syria and seized the Sunni town of Arsal in the northeast last Saturday. The gunmen withdrew from the town on Wednesday after five days of battles with the army.

The incursion by militants, including fighters affiliated to Islamic State which has seized large areas of Iraq and Syria, marked the most serious spillover to date of the three-year-old Syrian civil war.

Hariri earlier this week announced that Saudi Arabia would donate $1 billion in military aid to the Lebanese security forces to help them in the fight against extremists.

“There has been, in the last three years, a vacuum that has formed in the Sunni community. This was becoming increasingly dangerous because this community was becoming more and more radicalised,” said Michael Young, a political commentator.

“His return is probably an effort with the Saudis to re-assert a certain amount of control over the Sunni community.” - Reuters