Tanzania’s main opposition presidential candidate, Tundu Lissu, has been summoned to appear before the National Electoral Commission's ethics committee on Tuesday after he alleged that President John Magufuli had convened a meeting with district executive directors to discuss rigging October's election.

Senior election official Wilson Mahere said the allegation was meant to paint a picture that the poll would not be conducted in a free and fair atmosphere.

The registrar of political parties has also written a letter to Mr Lissu's Chadema party, saying his remarks posed a threat to national security.

District executive directors are required by law to act as constituency returning officers during the election. The government has denied Mr Lissu's allegation.