Whistle-blowing website Wikileaks has said that the detention of an alleged confidential source by the US military does not compromise its work.
Wikileaks founder Julian Assange told BBC News that other potential whistle-blowers should not be put off from sending material to the site.
The US has detained US military analyst Bradley Manning on suspicion of leaking classified material to the site.
Mr Assange would not confirm whether Mr Manning was a source.
"We endeavour to protect our sources," he told BBC News. "We do not know if Mr Manning is a source, but we understand there are allegations that are being taken seriously so we are naturally inclined to try to defend [him]."
The US army in Iraq has said that Specialist (Spc) Manning was in Kuwait and had been "placed in pre-trial confinement for allegedly releasing classified information".
One video reportedly posted to the site by Mr Manning shows a US Apache helicopter killing up to 12 people - including two Reuters journalists - during an attack in Baghdad in 2007. Two children were also seriously injured in the assault on the group, which contained some armed men.
Mr Manning's identity was reportedly revealed to the US authorities by a former high-profile hacker, Adrian Lamo, whom Mr Manning had contacted via e-mail and instant messenger.
During the course of their conversations, Mr Lamo told BBC News, Mr Manning boasted about handing over military videos and 260,000 classified US embassy messages to Wikileaks.
"At the moment he gave me the information, it was basically a suicide pact," Mr Lamo said.
He handed his name to US authorities because of concerns over US national security and because he did not want to be found to have been "obstructing justice" in the course of any investigation.
"I didn't want any more FBI agents knocking at the door," he said.
Mr Lamo has previously been convicted for hacking into the New York Times, Yahoo and Microsoft. He now works as a journalist and security analyst.
But Mr Assange questioned Mr Lamo's motives and credibility.
"He has broken the most sacred oath of journalism, which is confidentiality of sources."
Mr Assange also said that some of his account did not ring true.
"We do not recognise a number of the claims made by Adrian Lamo as to what Mr Manning allegedly related to him - they cannot be factually correct."
In particular, Mr Assange said that Wikileaks has no knowledge of the 260,000 confidential messages that Mr Lamo said Mr Manning claimed to have uploaded to the site.
However, as Wikileaks never divulges its sources, confirming the existence of the documents could implicate Mr Manning.
In response, Mr Lamo said he understood why Mr Assange would not concede to handling sensitive government data.
"I wouldn't admit to having them either," he said.
He also said that he was not approached by Mr Manning as a journalist.
"I was a private citizen in a private capacity - there was no source, journalist relationship," he told BBC News.
"I did tell him that I worked as a journalist. I would have been happy to write about him myself, but we just decided that it would be too unethical."
The story of Mr Manning's arrest was first reported on wired.com by Mr Lamo's long-term associate Kevin Poulsen, also a former hacker and now a journalist.
Wikileaks has established a reputation for publishing leaked material since its first appearance on the web in 2006.
In November 2009, it published what it said were 573,000 intercepted pager messages sent during the 9/11 attacks in the United States.
Previously it had posted a list of names and addresses of people said to belong to the British National Party (BNP) and a copy of the Standard Operating Procedures for Camp Delta, a document that detailed restrictions placed on prisoners at Guantanamo Bay.
Earlier this year, the website published a 2008 Pentagon report that said the site was considered a "threat to the US army".
The document says that "the possibility that current employees or moles within [the Department of Defence] or elsewhere in the US government are providing sensitive or classified information to Wikileaks.org cannot be ruled out".
It goes on to say that the "identification, exposure, termination of employment, criminal prosecution, legal action against current or former insiders, leakers, or whistleblowers could potentially… deter others considering similar actions from using [Wikileaks]".
The US government later confirmed to the BBC that the documents were genuine.
When the Pentagon document was leaked, the site stated that none of its sources had ever knowingly been exposed.
Now, Mr Assange said that Mr Manning's case should not put people off from contributing to the site.
"We have deliberately structured our operation to protect our sources under threat of criminal law," he said.
The site does not collect information about its sources and uses numerous web servers scattered around the world to host content.
Mr Assange said these were deliberately located in jurisdictions - such as Sweden - that could prosecute Wikileaks if it revealed a source.
It is currently advising the Icelandic government on efforts to increase legal protections for whistle-blowers in the country.
"We make it clear to [sources] that we will protect them."
He said this would apply to Mr Manning.
"Assuming that the allegations against [him] are true, we have taken steps to arrange for his protection and legal defence."