The Palestinian Islamist group Hamas confirmed on Sunday the death of two of its operatives in a bombing in Beirut.

A bomb exploded in the southern suburbs of the Lebanese capital on Saturday, targeting a car used by the operatives.

Speaking in Gaza, Hamas spokesman Ayman Taha said the victims were not high-ranking members of the organization.

It is unclear who was behind the attack, which took place in a parking lot near Hert Hreik district, near the Hamas offices in the area.

Security sources gave conflicting accounts of casualties, but reports early Sunday said that three security officials were killed and five other were hurt in the blast.

Ambulances rushed to the scene and security personnel sealed off the area within a 200-meter radius of where the bomb exploded, in a stronghold of the Lebanese Shi'ite group Hezbollah.

Hamas officials in Beirut were not immediately available for comment.

Rocked since 2005 by assassinations and war, Lebanon has enjoyed greater stability of late and formed a unity government last month. It had spent months without a functioning government after June elections in which a Saudi- and U.S.-backed coalition defeated Hezbollah and its allies.

Several Palestinian militants and Hezbollah members have been killed in Lebanon in recent years in attacks their organizations have blamed on Israel.

The Arabic language network Al Arabiya on Saturday reported that two Hezbollah men had been killed in the blast, possibly while trying to dismantle the bombs, which were attached to the car of Hamas' representative in Lebanon, Ali Barakeh.

Osama Hamdan, the Hamas representative in Lebanon, was not available for comment Saturday. A person who answered his mobile phone said he was not available and that he had no information on the explosion.

The explosion comes on the even of Ashoura, Shiite Islam's most important religious holiday.

Explosions in the area, which is almost completely controlled by the Shiite Hezbollah, are very rare. Hezbollah has its own arsenal with tens of thousands of rockets and missiles, which it says it needs to fight off any threat from Israel.

The area was bombed out by Israel during the month-long 2006 war with Hezbollah.

Hezbollah leader Sheik Hassan Nasrallah is expected to address tens of thousands of supporters commemorating the Ashoura holiday by video link on Sunday.