Venezuelan President Nicolas Maduro says he now doubts his Colombian counterpart is serious about making peace with FARC rebels.

Maduro says he doubts President Juan Manuel Santos' sincerity about a negotiated peace after what he called Santos' "stabbing of Venezuela in the back" by meeting with Venezuela opposition leader Henrique Capriles. Capriles alleged Maduro stole the April 14 presidential election through fraud.

Maduro also said late Thursday that he is weighing whether to continue Venezuela's participation in the Cuba-based talks between the Santos government and the FARC, or Revolutionary Armed Forces of Colombia, to end a half-century-old conflict.

The parties announced a 20-page agreement Sunday on land reform.

After being a longtime FARC haven, Venezuela played a key role in getting the talks launched last year.