The declaration of results was held up on Saturday after complaints of vote-rigging in two out of the 22 electoral districts, but Dissanayake said he did not believe that the irregularities had affected the final outcome.
"I do not believe that the reports I received warrants a fresh poll in those two districts," he told representatives of all political parties that contested Friday's parliamentary elections.
All political parties agreed, officials said.
However, four parties still wanted the vote annulled in a third area, the northern peninsula of Jaffna, after charges of rigging.
The commissioner overruled their complaint, which he said was based on "generalised allegations" about voting in Jaffna, a Tamil-dominated area which returns nine legislators to the 225-member assembly.
Rival Tamil groups charged that proxies of Tiger rebels organised impersonations to help guerrilla proxies edge out moderate Tamil politicians.
Election chief Dayananda
Dissanayake overruled complaints
"The next generation will curse you for legalising terrorism," moderate Tamil politician V Anandasangari told the commissioner during the meeting.
Anandasangari said the moderates stood against Tiger proxies despite death threats from the rebels.
The announcement came after election officials met with leaders of Sri Lanka's top political parties to discuss reported voting irregularities in parliamentary elections that could have delayed the final count by up to a week.
Early counting showed President Chandrika Kumaratunga's political alliance taking a strong lead against her long time rival, Prime Minister Ranil Wickremesinghe.
President Kumaratunga's coalition
has taken lead in initial tally
A Kumaratunga victory would almost certainly mean a shift in the direction of the peace talks, as the president, who survived a 1999 Tiger assassination attempt, has long distrusted the rebels' insistence that they want peace.
Despite the slowed results, the president's United People's Freedom Alliance was confident it would emerge the winner over Wickremesinghe's camp.
"The alliance has received the people's mandate to form the next government," Harim Peiris, Kumaratunga's top aide said on Saturday. "This is a clear repudiation of the prime minister and his government." The president herself is elected separately, and will remain in office until 2005.
Even if the party fails to win the necessary majority of 113 seats in Parliament, Peiris insisted it would be able to forge a ruling coalition.
Part of her support, he said, was her approach to the peace talks.
Kumaratunga has dismissed the prime minister's negotiations, saying he has made far too many concessions to the Tigers, a ruthless, secretive group that fought for nearly two decades for an independent homeland for the minority ethnic Tamils. Most Sri Lankans are Sinhalese.
The Sri Lankan PM says he has made
enough concessions with rebels
However, the Tigers have said they will be willing to negotiate with whichever party wins the elections.
Kumaratunga insists she wants peace talks, but she refuses to give the rebels the degree of autonomy they demand.
A fragile cease-fire has held for two years, but is already complicated by stalled talks, the corrosive rivalry between the president and prime minister and a split in rebel ranks.
Surprise support for a Buddhist monk-led party, the National Heritage Party, could also make things difficult for the Tigers.
The monk-politicians see themselves as defenders of a Sinhalese Buddhist culture they believe is under threat from the Tamil Tigers - who are Hindu - and Western-style consumerism.
"Our party will not join any government ... In Parliament we will sit as a separate group, and our support will be decided case-by-case"
National Heritage Party official
The monks could become powerful political players as each of the two main parties try to form coalitions and pass legislation.
They insist, though, that they will not join any coalitions.
"Our party will not join any government," party official Dhilak Karunaratne said on Sunday, before the meeting got underway. "In Parliament we will sit as a separate group, and our support will be decided case-by-case."
On Saturday, the Election Commission said that with 6 million votes counted - or about two-thirds the total votes cast - the president's party had captured 47% of the vote against 37% for the prime minister's United National Front.
The monk-led party tallied 6%, while a pro-Tamil Tiger party had 6%. That count had given 47 seats to the president's party, 32 to the prime minister's and three to the Buddhists. Because of the Sunday meeting, the release of further election results was halted on Saturday night until after those discussions.
Turnout was high for the vote, with officials saying about 75% of the country's 12.8 million eligible voters cast ballots.