Gaddafi, who registered to run on November 14, was among 25 candidates whose bids have been rejected from running in the December 24 election.
Libya's election commission has said that Saif Al Islam Al Gaddafi, the son of the former ruler and a major candidate in December's planned presidential election, is ineligible to run.
Gaddafi was one of 25 candidates disqualified in an initial decision on Wednesday pending an appeals process that will ultimately be decided by the judiciary. Some 98 Libyans registered as candidates.
Some of the other candidates initially approved by the commission had also been accused of possible violations by political rivals.
The military prosecutor in Tripoli had urged the commission to rule out Gaddafi after his conviction in absentia on war crimes charges in 2015 for his part in fighting the revolution that toppled his father Muammar Gaddafi in 2011. He has denied any wrongdoing.
Other hopefuls still in the running include warlord Khalifa Haftar, interim premier Abdulhamid Dbeibah and former interior minister Fathi Bashagha, as the commission said their submissions were valid.
Dbeibah vowed not to run for president as a condition of taking on his present role, but did not stand down from the role three months before the vote as is required by a contested election law.
Dbeibah has described the election rules issued in September by the parliament speaker, Aguila Saleh, as “flawed”. Saleh is also a candidate.
'War criminals' in vote
Disputes over the election rules, including the legal basis of the vote and who should be eligible to stand, threaten to derail an internationally backed peace process aimed at ending a decade of factional chaos.
Many people in western Libya also accuse warlord Haftar of war crimes committed during his 2019-2020 assault on Tripoli.
Hundreds of Libyans protested in Tripoli last week against "war criminals" running in the vote.
The final list of candidates is due to be published by early December, once verifications and appeals are completed.
Both presidential and legislative polls had been slated for December 24, but in early October parliament split the dates of the votes, postponing the legislative elections until January.