John Allwood, Mirror's chief executive, said the shareholding was no longer a core part of the group. "It needs to be disposed of," he said. "The timing depends on whether anyone makes us a good enough bid."
Yesterday Regional Independent Media, the newspaper publisher whose 200p a share bid for Mirror Group was rejected, said it was considering a cash offer for Mirror Group. It followed its rival Trinity by asking the Department of Trade and Industry to refer its interest in Mirror to the Monopolies and Mergers Commission.
Mr Allwood said Mirror had held talks with several interested bidders for SMG, adding that the shareholding might be sold for more than its current market value of pounds 106m. "I would like to think there was a premium to be paid for such a large stake," he said.
SMG, which owns the Scottish Television and Grampian ITV franchises as well as the Glasgow Herald, has long been seen as a takeover target for one of the larger ITV companies.
Analysts said the obvious bidder would be United News & Media, which is keen to expand its television interests and could combine the newspaper division with its Express titles. Carlton is also likely to be interested, but competition rules would prevent Granada from mounting a full takeover.
Flextech, the supplier of television channels, also has an 18.5 per cent stake in SMG, which it may want to sell for the right price. Combined with the Mirror shareholding, the stake could provide a perfect bid platform.
Analysts said a successful takeover of SMG would have to be pitched at more than pounds 12 per share. However, SMG is thought to be keen to hang on to its independence. Yesterday, shares in SMG rose 5p to 880p.
Mirror's decision to sell is one of the results of the strategic review conducted by Mr Allwood following his appointment as chief executive in January. Other conclusions include plans to sell the company's property development in Holborn.
Mirror also plans to stop investing in L!ve TV. Plans to relaunch the Sporting Life as a daily sports paper have been scrapped.
The conclusions were announced as Mirror reported a 9 per cent increase in pre-exceptional pre-tax profits to pounds 100m for the 53 weeks to 3 January.