By Dominic Casciani
BBC News home affairs
More than half of the firearms operations were in three police areas
The number of firearms operations rose by almost a fifth last year in police forces in England and Wales.
The Home Office figures show there were 21,181 authorised operations in the year to 31 March 2008, a rise of 17.5%.
Officers fired weapons seven times - up from three incidents the year before, but still fewer times than in 2001.
The figures show a drop in firearms operations in some police areas commonly believed to have significant gun crime problems.
The Metropolitan Police had the greatest number of operations in which firearms were authorised - 4,948. They were followed by the West Midlands with 2,350. Cumbria had the fewest operations - 92.
Bedfordshire saw 1,217 authorised armed operations in 2007-08 - up from 311 in 2003-04. Over the same period, the force's recorded gun crime offences hovered between 80 and 100 offences a year.
Concentration of cases
More than half of all recorded gun crime occurs in just three police areas - Greater Manchester, West Midlands and the Metropolitan Police.
The number of armed operations in the West Midlands rose from 822 in 2001-02 to 2,350 in 2007-08 - even though the number of recorded offences fell.
The figures show the number of operations fell in Greater Manchester - as well as in Merseyside and Nottinghamshire, two other areas widely associated in the past with gun crime.
Greater Manchester Police authorised 580 armed operations in 2001-02 and 497 in 2007-08. Merseyside's operations dropped from 1,020 to 829 and Nottinghamshire's to 270, from a high of 459 in 2003-04.
New ballistics service
The figures come as the Home Secretary opened a new firearms forensics centre in Manchester to help police to match weapons to crimes.
The National Ballistics Intelligence Service has three regional bases, with the Manchester unit serving forces in northern England.
Since Nabis became available in November 2008, Greater Manchester Police has submitted 113 cases to it.
Seven of these were confirmed by the service to have links to a number of other cases.
A recently recovered gun was this week found to be linked to four firearm incidents in the county over the past two years.