A suicide bomber killed himself and three soldiers when he detonated a car bomb at a Lebanese army checkpoint in the border town of Arsal, a security official said.

The Lebanese army said in a statement that four other soldiers were wounded in Saturday's attack on the checkpoint at Aqabet al-Jurd in the Arsal area.

The attack was claimed on Twitter by a group calling itself Liwa Ahrar al-Sunna in Baalbek, Arabic for the Brigades of the free Sunni Muslims.

It said the attack was to avenge the death of Sami al-Atrash, a suspect wanted in connection with car bombings targeting Lebanon's Shia armed group Hezbollah.

Atrash was killed on Thursday in a shoot-out with the army.

The army had described Atrash as a "dangerous terrorist" who was tracked down to a hideout in Arsal, where he was killed.

Arsal is home to thousands of Syrian refugees but also Syrian rebels and their Lebanese allies who have fled a Syrian army advance on the Syrian side of the border.

Lebanese Sunni fighters accuse the Lebanese army of conspiring with forces loyal to President Bashar al-Assad and the Lebanese Shia group Hezbollah, which has sent fighters into Syria to support Assad fight a Sunni-led revolt.

The attack hit just hours after a speech by Hezbollah leader Hassan Nasrallah, who said he was protecting Lebanon by fighting in Syria against Sunni fighters.

On Thursday, the Lebanese army killed a suspected Sunni bomb-maker as they raided his house in Arsal.

On Saturday, the army made further raids in Arsal, where they have set up checkpoints this month.

Lebanon has endured rocket and bomb attacks as the Syrian conflict spreads beyond its border, deepening sectarian rivalry in the country, which suffered its own civil war from 1975 to 1990.

Al Jazeera