Sri Lankan troops have surrounded a hotel in Colombo where Sarath Fonseka, the former army chief and presidential candidate, is staying along with some of his supporters.
The government has said the move has been taken for Fonseka's own protection, but it has ratcheted up tensions before the outcome of the presidential election, already declared by state media to have been won by Mahinda Rajapakse, the incumbent.
Mike Hanna, Al Jazeera's correspondent, reporting from close to the Cinnamon Lakeside hotel in the Sri Lankan capital, said that the hotel neighbourhood had effectively become a military area.
"There are hundreds of troops on the street outside the hotel. There are blockades by buses in the roads leading to the hotel," he said.
"To come through we had to go through the cordon of the troops, a search by the troops of our vehicle - certainly its a very, very intense military presence outside the hotel where Sarath Fonseka and his entourage are staying."
Brigadier Udaya Nanayakkara, the Sri Lankan military spokesman, said the troops had been deployed following information that army deserters were among about 400 people inside the hotel.
"We don't know what's their motive and as a protective measure, we have deployed troops around the hotel and people who go in and come out are being checked," Nanayakkara was quoted by The Associated Press news agency as saying.
In the final days of the campaign Fonseka had said the government had plans to either steal the vote or arrest him should he win.
Government allies, meanwhile, suggested that Fonseka's supporters might take to the streets, or that he intended to organise a coup with his own loyalists in the army if he lost the vote.
Both sides have denied the other's allegations and the election, which took place on Tuesday, was largely peaceful.
Early results showed that Mahinda Rajapakse, Sri Lanka's incumbent president, has taken a strong lead.
With only about a fifth of the ballots counted, Rajapakse was ahead with 60 per cent of the vote, but millions of votes - over 14 million Sri Lankans were eligible to vote in the election - are still to be tallied.
Hours later state television declared Rajapaksa the winner but there was no immediate confirmation and official results are expected at about 11:00 GMT.
On Tuesday, Fonseka found himself in the embarrassing position of telling reporters he "may have voted" but did not want to say if he had "due to security reasons".
|Fonseka's supporters say he was too busy fighting a war to register as a voter [Reuters]
He later admitted he was not on the voter rolls but supporters say he was too busy leading the war with the Tamil Tigers in 2008 when registration for the elections closed.
The government announced after polls closed that it would seek court action to disqualify him from the race.
However, the country's electoral commissioner later issued a statement saying Fonseka's status on the voter rolls was irrelevant to his candidacy.
Separately, Susan Hayward, a Sri Lanka analyst at the US Institute for Peace, told Al Jazeera that there had been reports of some irregularities.
"The Centre for Monitoring Election Violence has given some reports of rigging," she said.
Some people had questioned the results of postal votes, which had showed Rajapaksa with a slight lead, she said.