Atos Healthcare is paid to carry out work capability assessments to determine whether those receiving employment support allowance, previously incapacity benefit, can work.
Last week it forced Atos Register of Shame to close after claiming the experiences posted by disabled people who underwent an assessment were libellous.
The website was set up independently by Paul Smith, who suffers a number of physical and mental disabilities.
And Atos managed to close another website today by threatening legal action against CarerWatch Forum, a campaign group for carers.
CarerWatch founding member Frances Kelly said: “Atos has not been in contact with us.
“We have no idea which statements on the forum they are objecting to.
“There are thousands of posts and chat from members to one another.
“The host is American, has no interest in working out what is going on and isn’t prepared to risk leaving our forum up.
“It is a private forum for sick and disabled people and their carers and only members can read it.
“Now hundreds of sick and disabled people and their carers are not able to communicate – we don’t have the email addresses of our members.
“It has all been closed by the government agents Atos. How can this happen in a free country?
“The forum is mostly about sick and disabled people and their carers saying how frightened they are.”
Green Party member Alan Wheatley successfully applied for employment support allowance but is forced to reapply every six months “on the whim of quacks who disregard the Hippocratic Oath.”
He said: “It seems that Atos are piling on the pressure, especially regarding websites that are hosted in the USA. The bullying cowards.
“Their bark must be worse than their bite. Imagine what would happen to their reputation if they took legal action against CarerWatch and such self-help organisations in Britain.”
An Atos Healthcare spokesman added: “While we fully support the right of people to express their opinions, it is our duty to protect the reputation of our employees and company against false and malicious allegations.”