In the week that Bradley Manning learned he may face a lifetime in a military prison after he was found guilty of 20 out of 22 charges, John le Carré publicly questioned whether the Guardian is properly looking after another whistleblower, Edward Snowden.

Snowden is the 30-year-old intelligence analyst whose disclosures in the Guardian about the surveillance programmes of the US National Security Agency and the UK's GCHQ have made him a hunted man.

Notwithstanding the latest twist in the story, which saw Snowden leave Moscow airport last Thursday with temporary papers, his long-term future remains uncertain.

Le Carré, speaking on BBC Radio 3, expressed concern that Snowden has not been looked after by this newspaper. He said that democracies needed whistleblowers, but it seemed to him "extraordinary" that "the people to whom he was blowing his whistle, in this case the Guardian, did not take him on as one would normally an informant and look after his welfare later".

There are a number of profound questions raised by the Snowden revelations. However, I will concentrate on this one issue. Of the 54 emails the readers' editor has received on the NSA coverage only half a dozen have been in any way critical of the decision to publish. Two of those posed a similar question to Le Carré.

In an exchange of correspondence one reader put his concerns like this: "I would like to know how you justified this decision to publish without taking prior steps to ensure his wellbeing given the very real risks from so doing.

"At the very least I would now expect you to prevail on the UK government, making appropriate arrangement with the US to ensure he is granted safe passage anywhere in the world without risk of extradition. If the US argues that they have a legitimate case for a criminal action they should be reminded they are in breach of the constitutional right of free speech."

In a second email he said: "It would be a serious blot on your reputation if the paper appeared to be saying 'we are merely the medium, not the message'."

Any editor worth his or her salt knows that news organisation rely on people with the courage to break ranks and tell all. Whatever legal sanctions an editor may face, the burden of life-changing risk lies with the leaker. It is, after all, an editor's job.

Manning and Snowden may both be whistleblowers but their circumstances are different. Manning released thousands of US embassy cables to WikiLeaks, which in turn passed them on to news organisations, principal among those the Guardian.

Snowden went directly first to filmmaker Laura Poitras and then to Glenn Greenwald, a journalist working for the Guardian. On 6 June, Greenwald, in a video interview published on the Guardian site, asked him how he thought the US government might react, what it might do as a result of his public actions? Snowden said he thought he might be rendered [abducted]. He said: "That's a fear I will have to live under for the rest of my life, however long that may be… You can't come forward against the world's most powerful intelligence agencies and be completely free from risk … if they want to get you they will get you in time".

It wasn't possible to ask Snowden how he felt about the Guardian but I did ask Ewen MacAskill, a journalist who spent two weeks in Hong Kong preparing the story with Greenwald. MacAskill said that he discussed with Snowden and the Guardian's editor-in-chief, Alan Rusbridger, as well as the paper's US editor-in-chief, Janine Gibson, the Guardian's obligations. He said: "The first duty to a source is normally to protect anonymity but that did not apply in this case because Snowden made it clear from the start he was going to go public.

"On the issue of consequences, I raised with him several times in Hong Kong that he was almost certainly facing the rest of his life either in jail or on the run. He was well aware of that. For him, the issue of overarching state versus privacy overrode the devastating impact that publication would have on him personally.

"Our main duty to Snowden is to do him justice by publishing the material he gave us. He wanted a debate started about intrusion by the intelligence services into public life and that is under way, at least in the US." "I spoke to him as the first stories were published in the Guardian and he was more than happy with the presentation and the prominence we gave them. He was also happy with how we handled his going public and also subsequent stories such as GCHQ and Tempora, published after he had gone into hiding."

From Hong Kong Snowden flew to Moscow, a move of which the Guardian was unaware.

No editor can give a whistleblower a cast-iron guarantee. The most important issue in the relationship is to act honestly and fairly, taking every step to ensure that he or she has the best understanding of the consequences of his or her actions. And don't give up on the story or the storyteller. This has a long way to run.