Diallo said the extension would start on July 2 and last five years, at the end of which coup leader and acting president Captain Ibrahim Traore will be allowed to run in any elections.
A video of Traore signing the amended accord in front of a cheerful crowd was broadcast on Burkinabè state TV on Saturday.
The former ruling majority did not attend the talks, according to government press agency Agence d’Information du Burkina (AIB). Most political party activities have been suspended in the country under the military rule.
Burkina Faso, plagued by recurrent jihadist violence that has claimed thousands of lives for almost a decade, has seen two military coups in 2022.
The first one in January brought Lieutenant-Colonel Paul Henri Sandaogo Damiba to power, before being himself overthrown in September of the same year by Captain Traoré.
