Home Secretary Jacqui Smith said the Tackling Gangs Action Programme saw a 51% fall in gun injuries from 93 in October to 46 in February.

But analysis of figures published by the Home Office showed there were 13 gun killings during the six-month campaign compared with 12 in the same period the previous year.

The number of gun crimes recorded by West Midlands Police during the £1.5 million initiative was 106, compared with 77 in the same period two years earlier - a 38% increase. Liverpool also saw a rise from 47 to 59 offences.

Numbers fell in London compared with the same period two years earlier, from 431 to 374, and in Manchester, from 123 to 93.

A Home Office spokeswoman said: "In terms of looking at the local picture, we are saying that these are preliminary findings. There are lots of complex factors affecting gang crime and it is too early to draw real, firm trends from the data that we have.

"The overall data shows that different agencies coming together to tackle the problem can have a positive effect."

The Government also announced - on the day of the Crewe by-election - that it is to inject £5 million into a new fight against knife crime. About 10 towns and cities will be selected to run pilot schemes designed to combat knife-related crime.

The Home Secretary said a new anti-knife campaign will see the Government appeal directly to mothers in a series of advertisements. The ads will be placed in women's weekly magazines, and are designed to encourage mothers to talk to their children about the dangers of carrying knives.

The Department for Children, Schools and Families today also launched guidance for teachers on how to tackle gang-related incidents in schools.