BLIND Colombian former Farc liberation movement negotiator Seuxis Hernandez, best known as Jesus Santrich, has gone on hunger strike after his surprise arrest yesterday.

A US extradition warrant accuses him of trying to smuggle several tons of cocaine into the US.

More than 100 former guerillas and Farc sympathisers gathered to demand his release late last night outside the heavily guarded prosecutors’ bunker where Mr Santrich is being held.

Waving white flags emblazoned with the Farc red rose symbol, they denounced “judicial sabotage” by the government and its US backers, as riot police stood guard, flanked by a water cannon.

President Juan Manuel Santos defended the arrest on a US warrant as necessary to maintain the credibility of the peace accord, saying: “My hand won’t tremble to authorise the extradition.”

Mr Santrich, who joined Farc in his twenties before rising into the leadership, went to Norway in 2012 to begin negotiations with Colombia’s government before participating in subsequent talks in Cuba.

Even before details of his arrest were known, Farc leaders condemned it as a set-up that would undermine almost 7,000 demobilised freedom fighters’ trust in the peace process.

“This is the worst moment that the peace process has gone through,” said Farc chief negotiator Ivan Marquez.

The Supreme Court ordered increased protection in a safe house on Monday of Juan Guillermo Monsalve, one of two surviving witnesses to former president Alvaro Uribe and his brother Santiago’s links to death squads.

Other possible key witnesses have died in suspicious circumstances or been murdered.