A long-awaited ceasefire is officially underway in Colombia.

At midnight local time (5.00am Irish time) fighters from the main leftist rebel group, the Revolutionary Armed Forces of Colombia (FARC), put down their weapons.

The peace deal follows four years of talks with the government, and more than 50 years of bloodshed.

Some 220,000 people have died since FARC started their insurgency against political corruption and inequality in Colombia in the 1960s.

"Today I can say - from the bottom of my heart - that I have fulfilled the mandate that you gave me," President Juan Manuel Santos said on Thursday.

He was re-elected in 2014 after promising a peace deal.

"Colombians: the decision is in your hands. Never before have our citizens had within their reach the key to their future," he said in a televised address.

The deal will now be voted on in a referendum on October 2nd.

Polls suggest Colombians will back the deal, but Mr Santos will face fierce opposition from powerful sectors of the country who believe the only solution is to finish the FARC militarily.

Two former presidents oppose the accord -including the popular right-wing hardliner Alvaro Uribe.

Under the agreement, FARC will have non-voting representation in congress until 2018 and can take part in elections.

From then on, the 7,000 former rebels will have to win votes like any other party, Mr Santos said.