Portsmouth City Council approved the plans, which will heighten the roof of a part of the factory to house a 120pp triple-width MAN Roland Colorman press, on Wednesday.
The decision also signals the confirmation of Johnston Press's 15-year contract to print News International titles including The Sun and The Times at the centre.
Johnston Press finance director Stuart Paterson welcomed the news and said: "This cements our relationship with News International".
Paterson said that no order for the MAN Roland press had been signed, but confirmed that a deal is "imminent".
He added that no order had yet been placed for mailroom kit, which is also part of the investment, but said that the decision would be between Muller Martini and Ferag.
The triple-width Colorman with be the second to be installed by Johnston following the one to be installed at the publisher's new 60m Sheffield plant. It will be installed in a part of the Portsmouth plant which currently houses a four-unit 1988 Goss Community heatset press. Johnston plans to end heatset production by the end of the year, while the full-colour press will be commissioned by the end of 2007.
Two Goss Metro presses at the site, which were installed in the mid-1980s, will also be replaced. The News Centre also runs a Goss Universal press, which was installed in 2002.
Story by Josh Brooks
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