It was Redknapp's third signing in eight days after bringing centre-backs Sylvain Distin from Manchester City and Hermann Hreidarsson on free transfers from Charlton to the south-coast club and the surest sign yet of new owner Alexandre Gaydamak's financial commitment to making Pompey a top Premiership side.

The Franco-Russian tycoon is also planning a new state-of-the-art training ground at nearby Titchfield for next season and a £600million new 36,000-capacity waterfront stadium in 2011 but Redknapp has clearly persuaded him that an already highly-respected squad needs significant embellishment if Pompey are to maintain, let alone improve their top-10 status.

Portsmouth are refusing to name the exact figure they have paid Italian Serie A club Udinese for Muntari, officially describing yesterday's signing as a five-year deal "for an undisclosed fee" but they admit it has considerably eclipsed the £4.4million invested in Zimbabwe striker Benjani Mwaruwari, who arrived from French side Auxerre in January last year.

And that will not be the end of the spending. Redknapp loves nothing more than snapping up star players on free transfers at the end of their contracts, as he did with England defender Sol Campbell and Nigeria striker Nwankwo Kanu this season.

But there are further doubts over Kanu's future at Fratton Park even though the African ace, who hit 12 goals last term, has claimed he is close to signing a new deal.

Holland's PSV Eindhoven and Spain's Osasuna are reported to be tracking him and now Redknapp is believed to have made an offer for Mark Viduka, who has become a free agent at Middlesbrough.

Viduka was yesterday reported to have signed with Newcastle United by England's tabloid paper The Sun.

Redknapp also admitted an interest in French league stars Alou Diarra, currently with champions Lyon, and Rennes striker John Utaka.

For the moment, Redknapp is delighted to capture Muntari after trailing him for more than a year, having first scouted him during the World Cup when he scored for Ghana in a 2-0 win over the Czech Republic and described by his new boss as "the best player on the pitch" against Brazil.

Redknapp said: "He has a great left foot, great energy and can run all day. He can pass the ball, too. I tried to sign him in the last two transfer windows but Udinese didn't want to sell. So it is great that we have finally got him.

"Ghana have one of the best midfields in the world and he is a regular in their side. He is a player with a big future.

Muntari, who has won 26 caps for his country and scored eight goals, said: "Portsmouth is a fantastic club with class players like Pedro Mendes, Sol Campbell, David James and Kanu. They also have a great manager in Harry Redknapp."

But the African star also has a disciplinary record that could cause concern. He collected three red cards for Udinese last season and was also booked nine times.

Muntari played in a charity match at Portsmouth organised by Kanu the day after the FA Cup final and said: "The fans are great and they really love their football here.

"I'm really looking forward to playing in front of them and helping the club make a push for European competition."

It was believed in some quarters that his move to Pompey was held up by a dispute over his personal terms but a Pompey spokesman said: "There was never a problem in that direction. It was only minor details that caused the delay."

Redknapp insists he plays no part in the financial implications of transfer deals into Fratton Park, saying: "I leave all that to [chief executive] Peter Storrie.

The two players he has an eye on in France, Utaka and Diarra could, together, cost more than £10million.

And French champions Lyon may make difficult negotiating partners in Diarra's case now former Pompey manager Alain Perrin - sacked in November 2005 - has taken over there from ex-Liverpool boss Gerrard Houllier.