ALEXANDER McCall Smith, the author of the No1 Ladies' Detective Agency novels, has admitted he finds Scottish crime novels "strange" and said they show Scotland in a grim light.

The author – who has sold more than 20 million books in 46 different languages – said he was disappointed in the way some writers choose to portray Scotland as a "place of violence".

Discussing the genre of crime fiction dubbed Tartan Noir, McCall Smith said they were guilty of portraying a narrow view of Scotland.

He said: "Sometimes we present ourselves in a less than complimentary light, which is a pity. The portrayal of Scotland as a place of violence disappoints me.

"There is urban dysfunction and violence in Scotland, and aggression, but that's not the whole picture."

Scottish crime fiction has enjoyed a renaissance in recent years with authors such as Ian Rankin, Denise Mina and Louise Welsh, enjoying considerable time on the bestseller lists.

McCall Smith, a friend of Ian Rankin's who once gave his fellow Edinburgh author a cameo appearance in one of his Scotland Street novels, has won a huge audience with the offbeat humour of his novels.

He hit out at those who had labelled him "unduly optimistic" for not taking a negative approach when writing, saying that authors did not have to take a downbeat view in their work.

He said: "I get accused of being unduly optimistic and concentrating only on positive things, which I find a very strange accusation, because it is as if the role of the writer is to represent dysfunction and discord.

"Certainly that must be represented, but that is not the sole thing, this assumption that you have got to be grim to be a writer seems to me to be very strange.

"They feel this proper community and they may feel they are lacking it in their real lives.

"It is slightly artificial, [but] it appeals to some people. Scotland Street, for example, is widely read in India and they like [the fact] that it has got a strong sense of the local and local rootedness; people yearn for it in their lives."

The phrase Tartan Noir was first used by American writer James Ellroy when describing Rankin's Rebus series of books.

Although McCall Smith's Detective Agency novels appear in book shops' crime fiction section, he is renowned for the lightness of his stories and focus on his characters' eccentricities.

As well as the Detective Agency and Scotland Street novels, McCall Smith has scored a hit with his series The Sunday Philosophy Club, starring the Edinburgh philosopher and amateur sleuth Isabel Dalhousie.