Prime Minister David Cameron on Wednesday urged film makers, whose critical hits often fail to translate into commercial success, to focus more on the box office.

The movie industry is worth an estimated 4.2 billion pounds to the British economy each year, but much of that comes from blockbusters like the Harry Potter franchise that are bankrolled by Hollywood studios.

The government wants to see that change, after recent British hits like The King's Speech and Slumdog Millionaire proved that small budgets can be turned into box office gold.

The UK film industry, the skills and crafts that support it, and our creative industries more widely, make...an incalculable contribution to our culture, Cameron said.

Our role, and that of the BFI (British Film Institute), should be to support the sector in becoming even more dynamic and entrepreneurial, helping UK producers to make commercially successful pictures that rival the quality and impact of the best international productions, he added.

Just as the British Film Commission has played a crucial role in attracting the biggest and best international studios to produce their films here, so we must incentivise UK producers to chase new markets both here and overseas.

Cameron's remarks came ahead of a visit to Pinewood studios, the spiritual home of British cinema, where he was due to meet small and medium-sized businesses involved in film.

A review of the government's policy on the movie industry was also due to be published next week.

GOLDEN ERA?

Experts debate whether British cinema ever had the kind of golden era Hollywood enjoyed from the 1920s to 1960s, although it has regularly punched above its weight in terms of awards and ticket sales.

Most recently, The King's Speech won four Oscars including best picture in 2011, and earned $414 million (268.9 million pounds) in global ticket sales from a production budget of just $15 million, according to Boxofficemojo.com.

Two years earlier, Slumdog Millionaire was the big winner picking up eight Oscars including best picture and hitting $378 million at global box offices from a $15 million budget.

Official figures show that UK films accounted for 14 percent of the global 2010 box office tally of $31.8 billion. However, 12.6 percent was accounted for by UK movies wholly or partly financed and controlled by U.S. studios.

Some directors, including Ken Loach a long-time critic of Cameron's Conservative party, have argued that focusing on mainstream movie making could stifle the creativity for which British cinema is renowned.

Nobody knows who's going to see it (a film) until it's made, Loach told BBC Radio in response to Cameron's remarks.

If everyone knew the film that was going to make money before it was made we'd have no problem. I mean that's silly isn't it?

Loach also said that next week's review by former Labour culture minister Chris Smith was likely to miss an opportunity to loosen the grip of multiplex cinemas over what films audiences see.

If you want to fulfil the possibility that cinema has then you have to allow the films to be seen, he said. At the moment they are not seen.

But Loach conceded that one positive aspect of the recommendations expected in the review was that revenues from publicly funded films would go back to producers rather than the body that issued the funds in the first place.

(Reporting by Mike Collett-White, editing by Paul Casciato)