(AP) Honduras' ruling party said it had enlisted 300 lawyers to check results of the country's disputed presidential election for evidence of fraud.

Four days after Sunday's vote, the race was still too close to call Thursday.

With nearly 80 percent of the ballots counted, opposition Liberal Party candidate Manuel Zelaya had 49.7 percent compared to 46.2 percent for ruling National Party candidate Porfirio Lobo Sosa.

"We are analyzing the results of the elections to determine our future actions," said National Party attorney Ivis Discua. "There are many electoral documents that apparently have been altered or falsified."

He also said some polling places received more votes than they had registered voters, and called on the Organization of American States to investigate. OAS observers have said they saw no major problems.

Aristides Mejia, president of the Supreme Electoral Tribunal and a member of the Liberal Party, scoffed at the ruling party claims.

"Everyone accepts what has occurred in Honduras, except the National Party," he said.

Liberal Party spokesman Jorge Arturo Reina said that if there were irregularities, his party was not responsible.

"How could a party that isn't in power undermine an electoral process?" he asked. "Only the government can carry out fraud."

Reina, who Zelaya has said would be his foreign minister, called on the ruling party to concede defeat.

Electoral officials said computer problems have delayed the ballot-counting.

President Ricardo Maduro is prohibited by law from seeking re-election.