Lusaka – President Edgar Lungu held a slight lead early on Monday in Zambia's closely-fought election, as the opposition claimed the vote was rigged.Main challenger Hakainde Hichilema said late on Sunday that unexplained delays in releasing the results of Thursday's vote were a clear sign of fraud to produce a win for Lungu's Patriotic Front (PF)."Clearly this is rigging an election with the collusion of managers at the Electoral Commission of Zambia or commissioners," said the wealthy businessman, who is making his fifth bid for the presidency."We know that the PF, once they realised that they were behind, they wanted to force a re-run. The winner in the elections could have been announced a day or two ago."The electoral commission initially said results would be announced within 48 hours of the close of voting.By Sunday 85% of the results had been released, with Lungu ahead of Hichilema's United Party for National Development (UPND) by just 70 571 votes. The other seven presidential candidates were far behind.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.The electoral commission was on Monday meeting with representatives of political parties behind closed doors to verify the last batch of results.The PF has blamed Hichilema's party for the delays, saying they had raised numerous complaints with the electoral commission.Lungu took power only 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.With 132 out of 156 constituencies counted, Lungu was on Monday slightly ahead with 1 454 165 votes to Hichilema's 1 383 594.Recent constitutional changes require the winner to secure more than 50% of the vote, meaning a run-off is possible should neither candidate secure a majority in the first round.