A large explosion has rocked a stronghold of the Shiite militant Hezbollah group in the Lebanese capital Beirut, sending black smoke billowing into the sky and causing an unknown number of casualties, security officials said.

Hezbollah’s leader has urged his followers to prepare for mass demonstrations to topple the government if it ignored the militant group’s demand to form a national unity coalition.

Israeli forces took control of the strategic southern hub of Marjayoun today and warned that its fight against Hezbollah could grow wider and more severe if diplomacy fails.

A top Iranian envoy was in Syria today for talks on the Israeli-Hezbollah conflict in a meeting that brought together the guerrilla organisation’s two key sponsors, according to Iranian news reports.