The MPs say firms should not aid web censorship in China
Internet firms have been criticised by UK MPs for "collaborating" with state censorship of the web in China.
Businesses such as Microsoft, Google and Yahoo blocking some information was "morally unacceptable", the Commons foreign affairs committee said.
The MPs also called on the government to put pressure on China to relax its restrictions on the internet.
Their comments came in a wide-ranging report on east Asia which also attacked China's record on human rights.Maximum information
The committee said: "The collaboration of Western internet companies in the censorship and policing of the internet for political purposes is morally unacceptable."
The MPs agreed all web users should have access to the maximum possible information and said the UK should stress to the Chinese the economic damage such restrictions caused.
The internet firms argue it is better to offer Chinese users some information than none at all.
The report warned over China with the possible emergence of an "authoritarian bloc" with Russia.
It also raised concerns about the effects of Taiwan's exclusion from the World Health Organisation for the spread of bird flu, and over North Korea's nuclear programme.