BEIRUT (Reuters) - A former Hezbollah official was found dead in his apartment in a Beirut suburb, the state-run National News Agency said on Sunday.

The agency added that security forces immediately opened an investigation to find out the details of the incident, and is waiting for the arrival of the forensic doctor to determine the cause of death.

The agency gave only the first name of the former official and said he was named Ali.

Anatolia quoted Lebanese media as saying that the former Hezbollah official was Sheikh Ali Hatoum, and that he committed suicide at his home, without giving further details.

No other information was immediately available or his position in the Iranian-backed Hezbollah group was immediately known.

Hezbollah and the Israeli army exchanged cross-border fire on Sunday after a drone attack in the southern suburbs of Beirut, which is controlled by Hezbollah, in the heaviest cross-border shelling between the two sides since the 2006 Lebanon war.

Hezbollah blamed Israel for the drone attack, and Hezbollah leader Sayyed Hassan Nasrallah warned that the attack could be a signal that Israel was carrying out assassinations.