The legislation that is set to be relaxed would allow a newspaper owner such as Murdoch or the Daily Mail & General Trust to control a national TV station.
The move is being fiercely opposed by Labour peers, led by Lord Waheed Ali, Lord Melvin Bragg and Lord Puttnam, who believe that it threatens the UK media industry as it could give a media giant, such as Murdoch's News Corporation, too much power over the British media.
Murdoch already owns The Sun, the News of the World, The Times and The Sunday Times, as well as a controlling stake in BSkyB.
Speaking in interviews in national newspapers yesterday, Jowell sought to ease these concerns by setting out a number of restrictions that would prevent one company from becoming too powerful.
These include increasing Five's public service broadcasting commitments, and could also see it use a nominated news provider, to prevent it using Sky News. Five's news is currently provided by ITN.
Five has an audience share of 6% and only covers 80% of the country. Jowell said that if Five becomes a serious competitor with ITV then "we will tighten the obligations on Five in order to preserve its distinctive public broadcasting ethos".
The House of Lords, which is due to start debating the bill today, is also against legislation that would allow a-non EU company buying control of ITV.
Their opposition is based around concerns that if a US TV giant such as News Corporation or Viacom got hold of it, they would flood UK schedules with cheap imported US programming, which would harm the UK's production industry.
Jowell defended this part of bill by referring to US magazine giants such as AOL Time Warner and Hearst, which own UK publishers IPC Media and National Magazine Company respectively.
Jowell said: "What could be more quinessentially British than Good Housekeeping." NatMags publishes Good Housekeeping.
The opposition to the relaxation of UK media ownership rules mirrors the situation in the US. Yesterday, the Federal Communications Commission voted in favour of legisation that would allow newspaper owners to control TV and radio stations in the same market.
It also voted to lift the limit of the national audience a broadcaster can reach to 45%, up from 35%. This will benefit Viacom, which owns CBS and UPN, and News Corp, which owns Fox, because mergers have already given them a market share above the 35% ceiling limit.
However, the changes are expected to be opposed in the US Senate and Congress by both sides of the house. Senator Fritz Hollings, a Democrat, called the decision "dumb and dangerous", while former Senate majority leader Trent Lott, Republican, said he thought most Republicans in Congress would oppose some of the more controversial changes.
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