Zambia’s incumbent leader Edgar Lungu has been declared winner of the last week’s presidential election.

Election commission chief Esau Chulu announced that President Lungu was "duly elected" after releasing the final results from Thursday's election which put the president ahead of his main rival Hakainde Hichilema by around 200,000 votes.

President Lungu garnered 1,860,877 votes against Hichilema of the United Party for National Development (UPND) who got 1,760,347 votes.

But the opposition has disputed the outcome.

On Sunday, Hichilema had charged that unexplained delays in releasing the results were a clear sign of fraud to produce a win for Lungu's Patriotic Front (PF).

"We have started the process of petitioning this results. There are various cases of rigging and manipulation, ballot stuffing is one of them and we brought it to the attention of the ECZ," UPND legal counsel Jack Mwiimbu told reporters soon after the announcement was made by Justice Chulu.

"We hope court declares this election as a nullity."

Mr Mwiimbu said he believed their candidate has won these elections and that they had parallel voter tabulation that shows he has won by 54 per cent.

He said the commission went ahead to declare the winner despite the issues they raised of someone hacking into system but ECZ never responded.

Weeks of clashes

Copper-rich Zambia is usually known for its relative stability, but the run-up to the vote was marked by weeks of clashes between supporters of the rival parties which saw at least three people killed.

Election day — which saw a total of nine candidates run for president — was peaceful, with Zambian officials repeatedly issuing calls for calm to try to avoid a violent reaction to the results.

Zambia's electorate had also cast ballots in parliamentary and municipal elections as well as in a constitutional referendum.

The PF had blamed Hichilema's United Party for National Development (UPND) for the delays, saying it had raised numerous complaints with the electoral commission.

Lungu has been in office for just 19 months after he first took power last year when he beat Hichilema by less than 28,000 votes in a snap election following the death in office of president Michael Sata.

He was re-elected to a full five-year term.

Zambia, a British colony until 1964, recorded GDP growth of 3.6 per cent last year — its slowest rate since 1998.

The falling price of copper, the country's key export, has badly damaged the economy with thousands of jobs lost in mining and inflation soaring to over 20 per cent.