Leading article: Ministers and agencies in defence of the indefensible

The case of Binyam Mohamed has exposed divisions and distrust

It is, as the head of MI5, Jonathan Evans, noted at the start of his article in yesterday's Daily Telegraph, a rare departure for the intelligence services to comment in public on their activities. It must be even more rare, perhaps unique, for such an article to appear on the same day as a joint open letter on the same subject signed by the Foreign and Home Secretaries and published in this newspaper.

This united front suggests two things. It suggests, first, a shared concern that no one be able to drive a wedge between the Government and the intelligence agencies. It suggests, second, a deep sense of vulnerability on the part of the intelligence services – a vulnerability that, as they would have it, could impair British security.

The immediate impetus for both the article and the open letter was the judgment handed down by the Court of Appeal earlier in the week that found in favour of publishing parts of a document that the Government had wanted to keep confidential. The particular paragraphs related to the mistreatment of the British resident, Binyam Mohamed, in Pakistan. And it showed that British officials knew that what he was being subjected to, while stopping short, strictly speaking, of torture, breached undertakings that Britain had signed up to.

But the court judgment itself was probably not the only, or even the main, reason why MI5 and the Government so quickly and forcefully voiced their disquiet. What seems to have most concerned them was a section that was dropped from the final version of the ruling following an intervention by a government lawyer, but subsequently saw the light of day. That paragraph accused the intelligence services of perpetuating a general "culture of suppression" and suggested that MI5 might have misled the parliamentary Intelligence and Security Committee, which is responsible for its oversight.

Such charges were dynamite. Any admission of divisions between the security services and the Government could threaten the integrity of efforts to combat terrorism, while the charge of misleading Parliament would suggest that the intelligence services were essentially out of control. Neither could be allowed to stand.

At a state level, it was clearly important, even paramount, for MI5 and the Government to defend themselves. But the fact is that the observations to which they took exception were left out of the court's final judgment. What is more, at a more basic level, they are a distraction from the immediate matter in hand. Which is this: what did ministers and the intelligence services know about the treatment of Mr Mohamed, and when did they know it? And if, as it now appears, they knew at the time that his treatment contravened specific British undertakings, why did they do nothing about it?

David Miliband has said, and repeated in his letter, that the only reason for wanting to keep this information secret was that it had been obtained under the intelligence-sharing agreement with the United States. In other words, it was not the Government's to share. But the court's ruling was that Mr Mohamed's rights trumped this particular defence of national security, which it saw a pretext for keeping uncomfortable information under wraps. It is a supreme irony that one redacted paragraph – from a judgment that allowed publication of seven redacted paragraphs – revealed something even more sensitive than they did: the depth of distrust in our security services that this aspect of the US "war on terror" has left in its wake.