(Adds comments from Abdullah news conference)
By Mirwais Harooni and Hamid Shalizi
KABUL, June 15 (Reuters) - Rival camps in Afghanistan's presidential race each proclaimed to be leading the contest on Sunday, a day after the run-off was held and as officials were still tallying the hundreds killed or injured in election-related violence.
Observers and other officials in Kabul are worried that both candidates are setting the stage to complain about fraud and refuse to accept defeat should the outcome of the vote be close.
The United Nations on Sunday urged the candidates, former Northern Alliance leader Abdullah Abdullah and former finance minister Ashraf Ghani, to honour the election procedures, in the tallying of votes.
"The Secretary-General encourages the candidates and their supporters to respect the electoral process," the U.N. said in a statement.
On Sunday night, Abdullah said he was concerned about "engineered fraud" in the elections and questioned the voter turnout figures of over seven million released by the election commission.
"People participated in the second round but the turnout in no way was as much as released by the election commission given the security situation," said Abdullah at a news conference.
"Our observers were beaten and sent to jail. They were not given sheets to file complaints. We will not accept the announced turnout if it is not documented and substantiated."
He, however, claimed his party was still in a better situation than his opponent.
If successful, the vote will mark the country's first democratic transfer of power in its history. The winner will succeed President Hamid Karzai.
Abdullah, who dropped out of the 2009 run-off against the president, has spent five years in the opposition. His opponent, Ghani, is a former World Bank economist.
Both candidates appeared to set the stage for refusing to accept defeat in an election, likely marred by fraud, when the final results are announced at the end of July.
Ghani didn't comment on Sunday but his team said after the elections that he was the clear winner.
"The result is already very clear to everyone because Dr. Ashraf Ghani's observers were monitoring and at the same time were asking people's opinion," said a member of the Ghani team, former candidate Daud Sultanzoy.
Abdullah's camp has been equally categorical about the outcome, referring to their near 14 point lead in the first round.
Meanwhile, the election complaints commission said it had received 274 complaints of fraud so far, including 29 against its staff. Complaints can be lodged up to 48 hours after the vote closed at 4pm on Saturday.
Whoever wins the run-off will take over as most foreign troops withdraw, leaving behind a potent Taliban insurgency and a growing economic crisis.
The Taliban, who were ousted by a U.S.-led coalition in 2001, call the election "a sham show to install another fake regime in Afghanistan" and they launched hundreds of attacks on Saturday in an effort to disrupt the process.
More than 40 civilians were killed and over 70 wounded as a result, according to government officials. The figures did not include 11 people who had their ink-stained fingers chopped off by the Taliban as punishment for voting. Voters had to dip a finger in a pot of ink to prevent them voting twice.
The toll for soldiers and police was unclear as at least one battle continued through the night until Sunday morning in Kandahar, but officials said at 29 security personnel had been killed and over 70 wounded by 6 pm on election day.
Despite the bloodshed, millions of Afghans turned out to vote in the run-off and the electoral commission said more than seven million cast ballots, a similar turnout to the first round in April.
Both candidates support a security pact with the United States which is expected to result in a contingent of about 10,000 U.S. troops remaining in Afghanistan after the bulk of foreign forces withdraw by the end of the year. (Additional reporting by Bashir Ansari in Mazar-i-Sharif; Writing by Jessica Donati; Editing by Robert Birsel and Stephen Powell)