Negotiators for Colombia's government and leftist rebels are putting the final touches on a historic peace deal that they hope to announce in the coming hours.

Several government negotiators told local news media on Wednesday that all major obstacles to a deal have been cleared up in around-the-clock sessions taking place in Cuba. But some representatives for the Revolutionary Armed Forces of Colombia are cautioning on social media that some details remain to be worked out.

Speculation that President Juan Manuel Santos could announce a deal Wednesday night grew after the government published a photo of negotiators from both sides smiling under a banner reading: "The day is coming. We're on the road to peace."

Once negotiations conclude, the accord must still be ratified by voters in a plebiscite.