Bolivia's interim President Jeanine Anez will sign off on new elections that exclude Evo Morales on Sunday, which are seen as a crucial step to ending weeks of unrest in the crisis-hit country.

Congress on Saturday gave the green light for a new ballot after accusations the October 20 election, which Morales claimed to have won, was rigged.

Anez said she would sign the bill, approved by both houses during hours-long sessions, at 1400 GMT.

Among other things, the proposal annuls the results of the October 20 vote and allows for new elections to be held.

It also bars candidates who served in both of the two previous terms from seeking re-election for the same position.

That would prevent Morales -- Bolivia's first indigenous president who served for nearly 14 years -- from contesting the presidency in the new ballot.

Morales fled to Mexico after resigning on November 10 after losing the support of the military.

Bolivian prosecutors are investigating accusations of sedition and terrorism against Morales, after he allegedly called on supporters to maintain blockades in the landlocked country.

The next step will be for Congress to agree on a new seven-member electoral court, after members of the previous panel were removed for allegedly manipulating results.

The tribunal will be tasked with setting a date for the new vote that Anez has previously vowed to hold "as soon as possible."

New elections are seen as key to ending Bolivia's worst political upheaval in 16 years, which has deepened divisions between indigenous people loyal to Morales and Bolivia's mainly city-dwelling middle and upper classes.

At least 32 people have been killed in violence that erupted after the disputed election, with protesters' blockades causing severe fuel and food shortages in La Paz and other cities.