East Timor's prime minister has joined calls for a recount of votes from the first presidential election round.
Despite praise for the poll, claims of irregularities are emerging
Jose Ramos-Horta, a candidate in the election, said he was concerned by allegations of irregularities and intimidation of voters.
Another five of the eight candidates in the race filed a protest over the issue with election officials on Wednesday.
Mr Ramos-Horta is due to face a run-off with the ruling party candidate after no one won an outright majority.
According to preliminary results, the prime minister took 23% of the vote, trailing the Fretilin party's Francisco "Lu-Olo" Guterres, who had 29%.
The two men are expected to go head-to-head in a second round on 8 May, although the final results of the first round will not be known until early next week.
International observers, including the UN and the EU, had described Monday's election as generally calm, orderly and peaceful, with a high voter turnout.
But five of the candidates on Wednesday claimed the election had been undermined by intimidation of voters and irregularities with the count.
FIRST ROUND FRONTRUNNERS
Francisco Guterres, Fretilin Party - 28.79%
Jose Ramos-Horta, Independent - 22.6%
Fernando de Araujo, Democratic Party - 19%
Adding his voice to those concerns, Mr Ramos-Horta said he was alarmed that 150,000 voters - about 30% of registered voters - did not cast a ballot.
"Why? I don't know," he told reporters. "There has to be an investigation. I ask the UN for an explanation."
The national election commission was expected to meet on Thursday to discuss the possibility of a recount.
But spokesman Martinho Gusmao said any recount was unlikely to drastically affect the result.
"No candidate will win more than 30%," he said.
Monday's presidential election was East Timor's first since it won independence from Indonesia in 2002.
Many had hoped it would bring an end to the political tension and instability that has blighted the young country.
Last summer, more than 30 people were killed and thousands displaced in clashes between rival military factions.
There are fears that any prolonged uncertainty over the election could trigger more violence, although similar fears of unrest during the first round mostly proved unfounded.