The main opposition candidate in the Honduran presidential election has said he will not accept the poll count despite earlier vowing to respect it.
Salvador Nasralla says the electoral court is manipulating results.
With 88% of the ballots counted, President Juan Orlando Hernández, who is seeking re-election, is leading the official count by a narrow margin.
Earlier, thousands of protesters marched in the capital, Tegucigalpa, accusing the authorities of fraud.
Mr Nasralla and his supporters are deeply suspicious of the electoral tribunal, which counts the ballots.
Their distrust is partly due to the fact that the tribunal is appointed by Congress, which is controlled by Mr Hernández's National Party, and partly to the sudden reversal of Mr Nasralla's initial lead.
How results developed:
Monday 27 November, 02:00 local time (08:00 GMT) with 57.2% of votes counted:
- Salvador Nasralla leads by 5 percentage points (93,975 votes)
Tuesday 28 November, 18:15 local time with 65.7% of votes counted:
- Salvador Nasralla leads by 3.3 percentage points (72,697 votes)
Wednesday 29 November, 16:58 local time with 82.9% of votes counted:
- Juan Orlando Hernández leads by 0.1 percentage points (2,911 votes)
Thursday 30 November, 05:00 local time with 88.8% of votes counted:
- Juan Orlando Hernández leads by 0.8 percentage points (22,677 votes)
There has also been sharp criticism of the slow pace of the count, which came to a 36-hour halt after the first partial results were released on Monday.
Mr Nasralla called on his supporters to take to the streets in protest.
Tension was lowered temporarily on Wednesday when both Mr Nasralla and Mr Hernández signed a document vowing to respect the final result after every disputed vote had been scrutinised.
But another pause in counting attributed by the electoral tribunal to a computer glitch led to Mr Nasralla saying the document "had no validity".
"They take us for idiots and want to steal our victory," he said and again rallied his supporters to protest.
Police fired tear gas to disperse Mr Nasralla's supporters from outside the electoral tribunal.
He said that international observers were present at the count and assured voters on Twitter [in Spanish] that "it is impossible to modify the result".
The US state department has urged a quick conclusion to the vote count.
- 64-year-old former TV presenter and sports journalist
- Heads the Opposition Alliance Against the Dictatorship, a coalition of parties from the left and the right
- His parents are of Lebanese descent
- Ran for the presidency in 2013 but lost to Juan Orlando Hernández
- Has campaigned on a promise to battle corruption
Juan Orlando Hernández
- 49-year-old lawyer
- Heads the right-wing National Alliance
- Is the 15th of 17 children, two of his siblings are also in politics
- Is the first Honduran president to run for a second term after the supreme court lifted a ban on re-election
- Says that if elected, he will continue fighting Honduras's influential criminal gangs