Updated

Former Lebanese Prime Minister Saad Hariri has unexpectedly returned to Lebanon after three years in self-imposed exile.

Hariri arrived in Beirut on Friday morning and called immediately on Prime Minister Tammam Salam.

His unannounced return comes amid heightened tensions in Lebanon after Sunni extremists from Syria overran a town in the east, along the Lebanon-Syria border.

It has been the first wide-scale incursion by Syrian rebels into Lebanon. The fighters withdrew on Thursday, but there are concerns that the violence in the border town of Arsal could break out again.

Hariri, a prominent Sunni leader, left Lebanon in January 2011 after his government was brought down by the Shiite group Hezbollah and its allies.

He has since spent his time between Paris and Saudi Arabia, citing security concerns in Lebanon.