The call follows reports at the weekend that Carlton Communications and Granada were lobbying the government to allow them to take control of ITN, which provides news to the ITV network, Channel 4 and Five.
Currently, the ITV companies each own a 20% stake in ITN, with United Business Media, Daily Mail & General Trust and Reuters owning the rest.
The upcoming communications bill, to be made law in the new year, allows the maximum stake that any one company can hold in ITN to reach 40%, but with Carlton and Granada preparing to merge the two companies would already own 40%.
Shadow secretary of state for culture, media and sport John Whittingdale MP said: "The current ITN ownership rules are outdated and will act as a break on the development of the business.
"The government claims that the communications bill is relaxing rules on media ownership, yet the rules they propose will act as an obstacle to the merging of Carlton and Granada and will require the new company to divest part of its holdings," he said.
Whittingdale has called on the government to adopt a similar attitude to this question, as with other areas in the communications bill. "We will be tabling amendments to remove the existing ITN ownership limits," he said.
United Business and Daily Mail & General Trust are both thought to be likely to sell their stakes if the regulations are lifted, as neither is involved in television.
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