By Andrew Harding
BBC News, Bangkok
On the telephone from Rangoon, the businessman sounded desperate.
"I have looked everywhere," he said.
"The soldiers took my daughter off the street last week. I don't know if she is injured or what has happened to her. She is 18."
As Burma's military authorities continue to hunt down and arrest those suspected of involvement in last week's massive street protests, the fate of an unknown number of detained monks and civilians remains unclear.
A local United Nations official said his office was still looking for several staff members and their families.
The businessman hunting for his daughter had already visited two places widely thought to have been turned into makeshift detention centres - a sports complex at Rangoon's old race course, and a technical institute in the north of the city.
"The soldiers outside the institute told me it was empty," said the businessman, "but a friend in the neighbourhood told me two buildings were being used - one for female prisoners, and the other mainly for monks. I am at a loss as to what to do now."
"It's frightening to even think about the fate of those monks," said Shari Villarosa, the senior US diplomat in Rangoon.
She said conditions in Burmese prisons were "very grim, with reports of torture".
"The message has to get to the generals that this is not how a legitimate government acts in the 21st Century," she added.
But the Burmese authorities have shown no signs of responding to international pressure.
Military vehicles patrol Rangoon's streets before dawn, with loudspeakers announcing: "We have photographs. We are going to make arrests."
A former Burmese political prisoner, who spent a decade in jail for criticising the regime, said it was safe to assume from his own experiences that many of those detained would be tortured.
"The monks will have a very hard time," he said.
"I was blindfolded and subjected to sleep deprivation. They interrogated me in shifts for 11 days."
The man, who lives in Rangoon, wanted to remain anonymous for his own safety but urged the outside world to put pressure on the authorities by publicising the names of those arrested.
"That has to happen now. Not next week or next month."
Although the Burmese military has forced the protesters off Rangoon's streets, this does not appear to have broken the resolve of democracy campaigners.
Nilar Thein has been in hiding since the very first street protests, triggered by abrupt fuel price rises, were broken up by police and hired government thugs last month.
Although her husband and many other leading activists from the "88 Generation" (named after the last student uprising of 1988) are now in prison, Nilar Thein is still on the run with a handful of other activists.
Reached by telephone, she broke away from a planning meeting to declare: "There will be more sacrifices ahead. We must find a way to win this battle by joining hands with the monks and the public."
She urged members of the Burmese armed forces to stop fighting for "generals with blood on their hands".
Nilar, 35, left her five-month-old daughter with her mother-in-law when she went into hiding. Police are now guarding the house.
"I can't predict how long that will take."