Tanzanian president John Magufuli was on Friday declared the overwhelming winner of the elections by the National Electoral Commission, sparking a reaction by the opposition who allege fraud.

Magzfuli's victory means he will run for a second term and the ruling party CCM, which has been in power for decades, wins enough seats in parliament to change the constitution.

Some in the ruling party had called for the presidency's two-term limit to be extended if enough parliament seats could be secured.

The electoral body said Magufuli won 84% of the vote while his major rival Tundu Lissu of the Chadema opposition party got 13% of the total votes.

Lissu has rejected the result and called for peaceful protests and action.

"The results that have been announced since yesterday and that the electoral commission continues to announce today, therefore, are illegitimate results. They do not constitute, they do not express the true will of the Tanzanian people," Lissu said.

The US embassy in Daar, el Salam said while the vote went peaceful, there were credible allegations of significant election-related fraud and intimidation.

"There is a lot of complaints about the irregularities during the elections like fake ballot papers, but our leaders have forced their will on us, along with the police," said Chadema supporter Amani Saria.