A senior Zimbabwean election official said Tuesday he has resigned, just days after a colleague quit over the conduct of the vote that extended President Robert Mugabe's 33-year rule.

"Yes, I have resigned (from the Zimbabwe Election Commission)," law professor Geoff Feltoe told AFP.

"I am going back to the university. I have always intended to do so and I am going there," he said, referring to the University of Zimbabwe.

Feltoe refused to say if his decision was related to the conduct of the hotly disputed presidential and parliamentary elections last Wednesday that gave Mugabe another five-year term.

Fellow commission member Mkhululi Nyathi quit the body on Saturday, alleging that the polls did not meet the benchmarks of fairness.

Nyathi said his resignation had nothing to do with the outcome of the vote, which ended shaky power-sharing government formed four years ago by Mugabe and long-time rival Morgan Tsvangirai after violent 2008 elections.

Tsvangirai, who has unsuccessfully tried to unseat Mugabe three times, has vowed to challenge the result of the vote, branding it "fraudulent and stolen".

Tsvangirai has alleged widespread rigging and demanded a forensic audit of the voters' roll, ballot papers and voter registration certificates.

Western powers have also voiced serious concerns about irregularities in the election.