The US government's panic over the WikiLeaks revelations is extending to American campuses, with Columbia University warning students they risk future job prospects if they download any of the material.

The university's Office of Careers Services's cautionary note drew criticism from observers, who expressed alarm that the liberal bastions of academe in the US would be complicit in restrictions on access to the documents.

Disclosure of the warning came in the wake of a government ban on employees, estimated at more than two-and-a-half million people, using work computers and other communication devices to look at diplomatic cables released by WikiLeaks. The federal government advised employees that, though freely available on newspaper websites as well as WikiLeaks, they officially remain classified.

WikiLeaks dominated the Sunday morning talk shows, with views ranging from fears about what is still to come to calls for the Obama administration to adopt a more muscular approach.

Much of the debate centres on the need to restrict the number of people with access to classified material while avoiding a return to pre-9/11 when the number of people with such access was much more restricted.

Columbia University confirmed to the Associated Press that the Office of Career Services had emailed students at the university's school of international and public affairs, a recruiting ground for the state department.

The office said it had received advice from an alumnus who "recommends that you do not post links to these documents nor make comments on social media sites such as Facebook or through Twitter. Engaging in these activities would call into question your ability to deal with confidential information, which is part of most positions with the federal government."

The state department insisted no such advice had been sent out formally. Its spokesman, PJ Crowley, in an email to the Huffington Post, which had posted the Columbia University warning on its site, wrote: "This is not true. We have instructed state department employees not to access the WikiLeaks site and download posted documents using an unclassified network since these documents are still classified."

The US social security administration has joined the list of federal departments warning its employees not to browse WikiLeaks. It says in a circular: "Despite these documents being publicly accessible over the internet, the documents remain classified and SSA employees should not access, download, or transmit them. Individuals may be subject to applicable federal criminal statutes for unlawful access to or transmission of classified information."

The secretary of state, Hillary Clinton, back in Washington after a trip to Central Asia on which she was dogged by the WikiLeaks disclosures, attempted to laugh it off at a cultural awards ceremony. She told the audience it was extraordinary to stand in line to watch the different genres and generations pass, representing the breadth and depth of American artistry. She then joked: "I am writing a cable about it, which I'm sure you'll find soon on your closest website."