Diplomatic and political efforts are continuing to try to locate an Irish newspaper journalist kidnapped in Iraq.
Guardian reporter Rory Carroll has been in Iraq for nine months
Rory Carroll, a 33-year-old Iraq correspondent for the Guardian, is reported to have been taken by armed men while on assignment in Baghdad.
The paper's editor, Alan Rusbridger, said staff were "deeply concerned".
Irish Finance Minister Brian Cowen said the government was doing all it could and called on anyone with influence over the captors to help free him.
Three men arrested at the Baghdad house where Mr Carroll was reportedly snatched are being questioned.
A relative of the interviewee told BBC News they had had nothing to do with the kidnapping.
The commander of the Iraqi special forces involved in the search told BBC News his men were doing all they could to free Mr Carroll.
But he did not know which group was holding the journalist or what they wanted.
Deputising for Taoiseach Bertie Ahern, the Irish prime minister, Mr Cowan said: "I call on anybody who has any influence in that area to assist. We are trying to do all we can through our contacts."
The Irish foreign affairs minister, Dermot Ahern, urged the kidnappers to let Mr Carroll "go back to his family".
Mr Ahern told BBC News he was praying they would bear in mind he was "an Irish person not involved in any way" with the Iraqi conflict.
"We in fact granted him a passport in Irish, in our own language, in order to ensure that he would use this in such a way that to emphasise his Irishness in cases of difficulty."
Opposition leader Enda Kenny said opposition parties would assist the government in any way they could.
Earlier, Mr Rusbridger appealed to those holding Mr Carroll, saying: "He is in Iraq as a professional journalist - and he's a very good, straight journalist whose only concern is to report fairly and truthfully about the country.
"We urge those holding him to release him swiftly - for the sake of his family and for the sake of anyone who believes the world needs to be kept fully informed about events in Iraq today."
The Irish Anti-War Movement has also called for his release and said it would be contacting anti-occupation groups in Baghdad.
Chairman Richard Boyd Barrett said the journalist was "entirely innocent of any crime against the Iraqi people", adding: "No cause will be served by keeping him in captivity or harming him in any way."
He said Mr Carroll had attempted to provide balanced coverage of the Iraqi conflict, often exposing "the bloody reality of the war and occupation launched by George Bush and Tony Blair".
The Guardian said Mr Carroll had been in Baghdad with two drivers and an interpreter to interview a victim of Saddam Hussein's regime when he was kidnapped on Wednesday.
As he left the house where the interview had taken place, he was confronted by gunmen and he and one of the drivers bundled into a car. The driver was released about 20 minutes later.
RORY CARROLL'S CAREER
Graduate of Trinity College, Dublin
Joined Irish News in Belfast
1997 Northern Ireland young journalist of the year
Joined Guardian as home news reporter
Made South Europe correspondent in 1999
Was South Africa correspondent before going to Iraq nine months ago
Mr Carroll's father, Joe, told the BBC: "It was something we had been secretly dreading. We were hoping it would never happen."
Mr Carroll said his son had received specialised training for such situations.
"He knew we were worried but he used to reassure us and say it wasn't as dangerous as people outside think and if you observed basic rules of security, you'd be okay," he said.
"We knew he was playing it down for our sake. It was obvious danger.
The British Foreign Office said it was in touch with the Irish authorities about Mr Carroll's disappearance.
His disappearance came on the first anniversary of the abduction in Baghdad of Dublin-born aid worker Margaret Hassan, who was later apparently killed.