A former commander in the Farc rebel group in Colombia, Iván Márquez, has called on his followers to take up arms less than three years after the rebels signed a peace agreement with the government, reports BBC.
Iván Márquez appeared in a video in army fatigues and carrying a gun.
He announced that a "new phase of the armed struggle" was beginning.
He was one of the main negotiators of the peace deal and his announcement is a heavy blow to the peace process.
It shows Iván Márquez reading out a statement in front of a banner saying "While there is a will to fight, there'll be hope of winning".
He is surrounded by about a dozen men and women dressed in camouflage. Among them are two other senior former Farc rebels, Jesús Santrich, and the man known as El Paisa.
In his 30-minute-long statement, Iván Márquez says that he called for a return to arms because the Colombian state had "betrayed" the peace agreement he helped negotiate.
"In two years, more than 500 social leaders have been killed and 150 guerrilla fighters are dead amidst the indifference and the indolence of the state," he says referring to the high number of activists and former Farc members killed since President Iván Duque took up office.
In the recording, Iván Márquez also says that the new guerrilla group, which carries the old name, Farc-EP (Revolutionary Armed Forces of Colombia - People's Army), will pursue different tactics.
He says that group will only "respond to offensives" and that they will not carry out kidnappings for ransom but instead "seek dialogue" with local landowners and business people to try and convince them to "contribute" to their cause.
The video ends with Jesús Santrich shouting "Long live the Farc-EP!"
Iván Márquez is the nom-de guerre of Luciano Marín Arango. He was the number two in the Farc rebel movement before the guerrilla group signed a peace deal with the Colombian government in 2016.
He was a key figure in the peace negotiation which led to the signing of a peace deal in November 2016, leading the Farc negotiating team for the four years the talks lasted.
As part of the peace process, the Farc turned into a political party and was assigned a number of seats in Colombia's congress.
Iván Márquez was assigned one of the Farc's five seats in the senate. But days before he was due to take up his post in July 2018, he announced he would not do so in protest at the arrest of his Farc comrade, Jesús Santrich.
He went into hiding shortly afterwards and his only public appearance was in a video released in January.
In that video, he accused the Colombian government of failing to implement the agreements reached with the Farc and said he felt "disheartened". But at the time, he said he was still committed to peace.