Angola's biggest opposition party has vowed to contest last week's election results that saw the long-ruling MPLA win by a significantly reduced majority. The August 24 elections were the most hotly contested in the oil-rich country since its first multi-party vote in 1992. Results declared Monday placed the Movement for the Liberation of Angola (MPLA) as the winner with 51.17% of the vote, securing a second term for President Joao Lourenco. But the opposition National Union for the Total Independence of Angola (UNITA) said it "does not recognise the results" from the national electoral commission. It vowed to file a legal claim "which will have the effect of suspending the declaration of the final results", the party's secretary general, Alvaro Chikwamanga Daniel, said in a video recorded overnight. During the final phase of counting, the former rebel movement-turned-opposition-party claims "not to have been informed of the decision" by the electoral commission to ratify the results and not to have received a "copy of the tables of the final results". Candidates have 72 hours after the announcement of results to file a claim to the Constitutional Court contesting the ballot. Four of the 16 electoral commissioners did not sign off on the final results, casting doubts about the process. The MPLA has been the only party to govern the oil-rich country since it gained independence from Portugal in 1975, but saw its poorest showing in this year's ballot, down from its victory with 61% in 2017. UNITA made significant gains from the 2017 elections, earning 43.95% this round, compared with 26.67% in the previous vote. It did particularly well in the capital district of Luanda, where it won a majority. While the ballot count was underway, UNITA leader Adalberto Costa Junior announced last week that there were discrepancies between the commission's and his party's tallies. Costa Junior also called for an international panel to review the count. The charismatic leader saw a rise in popularity among young voters who want change for the country's struggling economy and plagued by poverty and inequalities. "It is in the interest of all Angolans that the (electoral commission) does not avoid comparing" its tally with those conducted by political parties "which represents the electoral truth," Monday's statement from UNITA said. Less than half of the approximately 14.4 million registered voters took part in the ballot that saw eight parties listed. UNITA had also contested the 2017 vote, which did not result in the overruling of the winner.