Colombian voters rejected a peace deal with Farc rebels in a surprise outcome that risks prolonging a 52-year-old conflict and plunges the country's future into uncertainty.
By a razor-thin margin of 50.25 to 49.75 per cent, Colombians voted against the peace accord, in a Brexit-style backlash that defied pollsters' predictions and left supporters of the deal in tears.
After nearly six years of negotiations, a half-century war that has killed 220,000 and displaced seven million from their homes is not over.
"I am the first to recognise the result," said Colombian President Juan Manuel Santos, flanked by members of the government peace negotiating team, who looked stunned. "Now we have to decide what path to take so that peace will be possible. ... I won't give up."
Surveys had predicted an easy win for the Yes vote by a margin of 2 to 1. Instead the result delivers a crushing blow to Santos, who since 2011 has pursued the peace deal with single-minded determination and to the steady detriment of his own popularity. He took an extraordinary risk by insisting that the accord - the product of tedious, grinding negotiations with the Farc - would only be valid if voters gave their blessing.