BEIRUT, Oct 18 (Reuters) - Lebanon"s Hezbollah group has 100,000 trained fighters and the group has never been stronger, its chief, Sayyed Hassan Nasrallah, said in a televised address on Monday, days after Beirut witnessed the worst street violence in over a decade. Seven people were killed on Thursday when a gun battle erupted as protesters from the Shi"ite Hezbollah and Amal groups were on their way to demonstrate against the lead investigator of the Beirut port blast. Hezbollah has accused the Christian Lebanese Forces party (LF) of being responsible for Thursday"s violence, an accusation which its head, Samir Geagea, has denied. "I advise the Lebanese Forces and its head to give up on this idea of civil war and internal strife completely," Nasrallah said. "Your calculations are wrong ... the region has never seen a Hezbollah as strong as now."