Russian billionaire Roman Abramovich has completed the first stage of a multi-million pound makeover of his Sussex mansion.

Mr Abramovich, 37, bought the £12 million Fyning Hill estate at Rogate, near Midhurst, from Australian media mogul Kerry Packer.

A pool house, sauna and lavishly-equipped gym have now been completed on the site and a Twenties building has been demolished.

It will be replaced by a quintessentially English guesthouse in the style of Edwardian architect Sir Edwin Lutyens.

Architects Douglas Briggs Partnership say the house's sloping roofs, tall chimneys, materials and methods of construction will be typical of the locality.

Mr Abramovich, who was named Britain's richest person earlier this year, is worth an estimated £7.5 billion.

His estate already has three polo grounds, formal gardens, a lake, a 50ft outdoor swimming pool, a tennis court, a clay pigeon shooting site, a trout lake, a go-kart track, a rifle range and an equestrian centre.

It also contains a second house, six cottages, a staff flat and four guest flats.

Mr Abramovich, who bought Chelsea Football Club, concentrates his business activities on trading oil products out of Russia's largest refinery in Omsk, western Siberia.

He has a controlling interest in Russian oil giant Sibneft, shares in national airline Aeroflot and a television company, among other holdings, through Millhouse Capital, registered in Britain.

He owns a Russian ice hockey team and a 42-hectare country estate near Moscow.