There have been complaints of fraud and irregularities in the vote counting
Iraq's election commission has rejected calls from the president and prime minister for a recount of votes cast in the general election on 7 March.
An election official said a recount of all votes would be impossible and was unnecessary because of checks on fraud.
Earlier, President Jalal Talabani and Prime Minister Nouri Maliki backed calls for a manual recount of votes.
Partial results indicate a close race between Mr Maliki and former Prime Minister Iyad Allawi.
But the long delay in announcing the full results has led to growing allegations of fraud and demands for a recount.
"It can't be done, it can't, we can't start all over again and count the votes manually," Saad el-Rawi of the Independent High Electoral Commission (IHEC) told BBC Arabic.
"We don't say it's impossible," he added, "but it will take a lot of time.
"We have more than 50,000 polling stations and 350,000 election officials. Do they want us to resend all the ballot boxes back to the stations and call back all the officials?"
Other IHEC officials have said vote recounts from particular districts could be requested if candidates thought errors had been made.
Change of tone
With just over 90% of the votes counted, IHEC said on Saturday that Mr Allawi's Iraqiya political bloc was ahead by nearly 8,000 votes nationwide.
By Andrew North, BBC News, Baghdad
The actual business of counting individual ballots from Iraq's elections was completed soon after the 7 March vote, in each province.
So why is it taking so long to announce complete results?
According to officials at election commission headquarters in Baghdad, it's because of the scale and complexity of the task - with 6,000-plus candidates and 86 parties across the country.
Every piece of data is entered into the computers twice, by different teams working separately - to guard against fraud and errors.
The two sets of results are then re-checked by the computers. If they are not within the agreed margin of error, election workers have to start the process again.
There is an additional manual check before figures for each province are finally cleared for release.
Officials insist these checks mean it is almost impossible to rig the result, despite the accusations.
But it seems the election commission badly under-estimated the size of the task. Their computer servers have crashed more than once.
But Mr Maliki's State of Law alliance was ahead in seven of 18 provinces - meaning he stands to get more representation in a future parliament as seats are allocated based on the outcome in each province.
"As the president of the state, authorised to preserve the constitution and to ensure justice and absolute transparency, I demand the Independent High Electoral Commission recount the ballots manually starting from Sunday, March 21," Mr Talabani said in a statement.
He did not say which provinces' votes should be recounted.
Mr Maliki has also backed calls for a manual recount of votes but has not made it clear if the count should be nationwide.
On Wednesday he called for a recount in the Baghdad region.
Mr Maliki's tone has changed from last weekend, says the BBC's Andrew North in Baghdad. At that time he appeared to have a firmer lead and said the election process appeared to be going smoothly.
International observers have largely approved of the conduct of the election.
But Mr Allawi, who headed the country from 2004 to 2005, said the vote had been "grossly mismanaged" and that full results should have been declared days ago.
Final results - after complaints have been investigated - are due by the end of the month.