It is fitting that when he started filming, Anthony Minghella did not know if The No 1 Ladies Detective Agency would end up as a feature or a TV film. After all, this is a director who made his international name as an Oscar winner for such sweeping cinematic epics as The English Patient. But he got his break as a director for UK television.

"I vacillated and I am still vacillating," says Minghella, on the Botswana set in August (he and his team are now in post-producion in London and Los Angeles). "I didn't want to commit (the project) to either the small or the big screen because I wasn't sure what we would get.

"There's a tension in the material between small episodes of venial sins and the most cinematic landscape you can imagine. I suppose it depends on which feels more heightened once we have put the film together. Is it better to enjoy those landscapes and characters on a small screen or lift them onto a big screen' I really don't know."

The adaptation of the first of Alexander McCall Smith's whimsical Botswana-set novels about private investigator Precious Ramotswe, will screen on TV in the UK and the US and may enjoy a theatrical release elsewhere. Backed by the BBC (the film will screen on BBC 1 next Easter), The Weinstein Company and the Botswana government, there are also plans to develop it into a TV series.

The project has broken new ground and not just because it is the first international production to film entirely in Botswana (the crew is a mix of Brits and South Africans). The cast features US and UK actors including Jill Scott, David Oyelowo and Lucian Msamati, with 21 of the 48 speaking parts played by African actors.

"It's the first mainstream global piece of TV with all black characters that's promoting Africa in a positive way," claims UK producer Tim Bricknell, who also worked with Minghella on Cold Mountain. The project was originated with producer Amy Moore, who optioned the books and took them to Minghella and Sydney Pollack's Mirage Enterprises.

The script is by Minghella and Richard Curtis. "It's not simply that he did the jokes and I did the boring stuff," Minghella smiles. He explains that much is gleaned between the lines about the idiosyncrasies of everyday life in Botswana. He hopes the image of Africa portrayed will be at some distance from the stereotypical media headlines, which so often feature disease, famine and dictatorships.

Botswana has a very limited film-making infrastructure - it has had its own television station for less than a decade - and Minghella says it would have been far simpler to shoot across the border in South Africa. But investment from the Botswanan government - $5m of the total $13m budget - made up for the extra costs of shooting in locations where the books are set.

The knock-on benefits for tourism in Botswana also played a role in the decision. Tourism, cattle and diamonds are the country's big economic drivers.

What's more, the production fits with the state's wish to build Botswana as a film-making hub. One of the natural advantages is that the territory is calm and orderly compared to many African nations. Many of the mostly South African crew said they felt relieved they did not have to worry about their personal safety.

"You could accuse it of being neither fish nor fowl because it's a film with pretty much exclusively an African cast and crew, based on a novel by a man born in Zimbabwe who lives in Scotland, written by two English writers, one of whom is directing," says Minghella. "Its provenance is curious but I think its intentions are clear and coherent, which is to celebrate Africa."