TOPWRAP 6-Protesters hold Bahrain square; shooting in Libya

* Libyan security forces shoot to disperse mourners

* Bahrain protesters back in square

* Bahrain govt says dialogue with opposition has begun

* Rights group says death toll in Libya now 84

(Updates Bahrain, Libya details, adds Saudi, Egypt)

By Cynthia Johnston and Frederik Richter

MANAMA, Feb 19 (Reuters) - Protesters in Bahrain took back a symbolic square on Saturday and Libyan security forces shot more people demonstrating against longtime leader Muammar Gaddafi as uprisings sweeping the Arab world challenged its rulers.

The anti-government demonstrators in Bahrain swarmed into Pearl Square in Manama, putting riot police to flight in a striking victory for their cause and confidently setting up camp for a protracted stay.

In Libya's second city Benghazi, security forces killed at least three more people but withdrew to a fortified compound, a witness said, after the worst unrest in Gaddafi's four decades in power.