A former parliamentary speaker and an ex-capital city mayor are among 75 officials who have announced their resignation from the ruling party in Burkina Faso, ratcheting up political tension before elections scheduled for next year.

In a letter published over the weekend announcing their resignations, the officials said democracy had "disappeared" from President Blaise Compaore's Congress for Democracy and Progress party.

They also criticized Compaore's plans for a controversial new Senate that spurred large-scale demonstrations last year.

Critics believe Compaore plans to use the new Senate, approved by lawmakers last May, to change a rule that limits presidents to two five-year terms. Compaore has been in power since 1987. Under the current rule, he would not be able to run again once his current term expires in 2015.