ISLAMABAD - A United Nations investigation has found insurgent attacks targeting the recent presidential electoral process in Afghanistan caused nearly 460 civilian casualties, including 85 deaths.

The special report by the U.N. Assistance Mission in Afghanistan (UNAMA) released Tuesday, blames more than 80 percent of the casualties on the Taliban's deliberate campaign of violence and intimidation to disrupt the September 28 election.

The insurgent group had repeatedly made public statements warning Afghan voters to stay away from the election and ordered its fighters to attack organizers as well as security forces guarding the electoral process.

On the polling day alone, it noted, the violence killed 28 civilians and injured around 250 others. More than one-third of civilian casualties were children.

UNAMA not only documented civilian casualties but also highlighted a pattern of abductions, threats, intimidation and harassment carried out by the Taliban against civilians leading up to and during the election.

"Many Afghan people, however, defied the threats and cast their votes - brave acts that I commend," said Tadamichi Yamamoto, head of UNAMA.

He denounced as unacceptable and a breach of international humanitarian law Taliban attacks against voters, election workers, campaigners, rally sites and polling centers.

"These attacks, along with public statements made by the Taliban, revealed a deliberate campaign intended to undermine the electoral process and deprive Afghan citizens of their right to participate in this important political process, freely and without fear," said Yamamoto.

The initial official results from the Sept. 28 polls are not expected until late October, while final results are expected next month. Initial assessments suggest participation in the first round of the presidential vote is at a record low, mainly because of security concerns.

The Afghan Independent Election Commission (IEC) has also run into technical and logistical issues in gathering and transferring biometric data to its servers from over 26,000 biometric devices used to record fingerprints and pictures of voters, which may delay the results.

Two rival candidates, Abdullah Abdullah, and former warlord Gulbuddin Hekmatyar, have already questioned the transparency of the electoral process, alleging a large number of votes cast for incumbent Afghan President Ashraf Ghani were fraudulent and without biometric verification.

Abdullah and Ghani have already claimed victories, raising fears of a repeat of what happened in the 2014 fraud-marred Afghan presidential election, when the United States had to intervene to help the two men negotiate a power-sharing deal, ending months of nationwide chaos.