The opposition in Burkina Faso has agreed to rally behind any challenger to President Roch Kaboré who reaches the second round in November's elections.

Eight presidential candidates and 22 opposition parties signed the agreement on Tuesday.

Should two opposition candidates reach the second round, then their respective parties would support them, the agreement states.

The first round of the presidential election will be held on 22 November.

Opposition leader Zéphirin Diabré said the agreement was "historic" and would enable "the writing of a new chapter", according to AFP news agency.