Soldiers, sailors and airforce personnel will not be able to blog, take part in surveys, speak in public, post on bulletin boards, play in multi-player computer games or send text messages or photographs without the permission of a superior if the information they use concerns matters of defence.

They also cannot release video, still images or audio - material which has previously led to investigations into the abuse of Iraqis. Instead, the guidelines state that "all such communication must help to maintain and, where possible, enhance the reputation of defence".

The regulations, issued by the Directorate of Communication Planning, come in the wake of the row over the MoD allowing two of the HMS Cornwall sailors held captive in Iran to be paid for their stories. Receiving money for interviews, conferences and books which draw on official defence experience has now been banned.

The MoD document, circulated last week, covers "all public speaking, writing or other communications, including via the internet and other sharing technologies, on issues arising from an individual's official business or experience, whether on-duty, off-duty or in spare time".

The rules have provoked consternation among the ranks, with human rights lawyers saying yesterday that they could be in contravention of Article 10 of the Human Rights Act, which allows for freedom of expression. The rules apply not only to full-time forces but to members of the Territorial Army and cadets whilst on duty, as well as MoD civil servants.

Service personnel are currently bound by Queen's Regulations, which mean they must seek permission before speaking to the press but are free to blog and take part in online debates. However, many have spoken out anonymously on issues such as poor kit, housing and the treatment of wounded service personnel evacuated from combat zones. Criticism of the RAF in Afghanistan and the state of the ageing vehicles being used there have all appeared in the press.

An unofficial soldiers' website, arrse.co.uk, was full of angry debate about the issue yesterday. One poster said: "Why does it not occur to MoD that if it did things properly, and treated its people well, they wouldn't feel the need to bring things into the public arena quite so often, and they wouldn't need to spend so much time covering-up?"

Another suggested that the rules were intended to silence the average "tommy" while senior personnel were free to speak to the media without fear of reprimand. "Every single leak of significant information to the media, certainly in the last six months, has come from the top down. Not the other direction," he said. "Should Cpl Bloggs, or Major Good Bloke in some Platoon House in downtown Helmand-on-Styx complain in a private letter that he hasn't enough ammo to despatch the Queens' enemies, or the RAF really should try harder to deliver it, it's 'March in the guilty B*stard' and 'conduct prejudicial to good order' and discipline and finger-wagging all round."

The MoD's director general of media communications, Simon McDowell, denied that the guidelines were a form of censorship or gagging.

"We are trying to give straightforward, clear guidance that is up to date. The existing regulations were confusing and didn't include things like accepting payment. It applies to communicating about defence matters, not personal things. Particular things can impact on operational security; information which somebody can get a hold of. Even a little photograph sent from Afghanistan on a mobile phone could endanger people's lives and break operational security."

He added: "It is not gagging. It is setting out procedures so people know what the rules are." Those infringing the rules would be dealt with on a case by case basis, he said. "There is now far less of a chance of having the kind of mishaps that we had with Iran now there are clear guidelines."

Mr McDowell said that the MoD was experimenting with authorised blogs from Afghanistan. It was also seeking "legitimate outlets for people to express themselves".

Geoffrey Robertson, QC, a leading human rights lawyer, said that the guidelines were likely to contravene the Human Rights Act. He said they reminded him of the "catch-all" section of the old official secrets act, which made it a criminal offence to disclose information without lawful authority. The discredited section, which was repealed in 1989, "stopped soldiers from revealing the brand of tea served in the MoD canteen", he said.

"It's increasingly important, given Britain's escalating foreign troop engagements, often in conjunction with less-disciplined forces, that soldiers, officers and officials can speak frankly to the media about their engagements without having their honest briefing subject to any spin," Mr Robertson said.