Privatising Channel Four would badly damage the quality of its output and probably see the broadcaster fall into foreign hands, peers have warned.
The House of Lords Communications Committee urged the Government not to sell off the network in order to raise billions of pounds for the Exchequer.
It warned Culture Secretary John Whittingdale that any benefits would be out-weighed by negatives.
A report by the committee rejected claims by Mr Whittingdale that privatisation could help secure the future of the public broadcaster.
Committee chairman Lord Best said: "Channel Four is an important and much-valued part of the nation's media landscape, and boasts an array of innovative and creative programming as well as a strong commitment to public service broadcasting.
"This is evident from its distinct news and current affairs coverage, its much-lauded contribution to cinema through Film4, and its pioneering approach to on-screen diversity. However, we fear that these qualities would be jeopardised were the channel to be sold off."
Lord Best added: "We believe that news output would be especially vulnerable, given its prime time position in the schedules. We are calling on the Government not to take forward any ideas to privatise Channel Four, wholly or in part, as it is our view that the risks from selling it off are greater than any benefits that may arise.
"In our report we also conclude that the current business model is in fact working well for the broadcaster, and we do not believe that Channel Four is too vulnerable to continue as it is.
"We add that if the Secretary of State does pursue a privatisation proposal, we would call on him to ensure safeguards are in place to guarantee that there was no negative impact on the viewer or the UK's creative industries."
The committee warned that unless the Government put reconstructions on any future sale, the broadcaster would probably be bought by foreigners.
"We are concerned about the implications of purchase by a foreign buyer, and urge the Government to lay down strict conditions to protect the integrity of the channel," the report stated.
The Lords found that the channel's current business model is sustainable, at least until the end of its current licence period in 2024.
The report criticised the standard of the channel's programming aimed at older children and young adults, insisting it is "unsatisfactory".