Officers believe as many as 54 of the capital's most dangerous gangs have "tentacles" in other towns and cities, operating like business franchises.
The warning came a day after co-ordinated raids in Thames Valley, Edinburgh, Essex, Bedfordshire and London in which 29 people were arrested in an operation targeting the London-based GAS gang.
But Deputy Chief Constable David Thompson of West Midlands Police, who speaks on gangs for the Association of Chief Police Officers, said significant headway was being made in dealing with gang-related crime, with a decrease in gun and knife crime.
Mr Thompson said gangs had always relocated in search of opportunities to make money or in response to pressure from police on their home turf.
Following Thursday's raids, Detective Chief Inspector Tim Champion, from the Met's Operation Trident gang crime command, said: "What we are noticing is that gangs are spreading their wings, so rather than working in London, they are going into the counties, and even Scotland, to deal drugs. So basically it's an expanding trade."
Mr Thompson said organised criminals have "never really recognised boundaries".
"I don't think there's anything new particularly about what's being discussed. I think there are some particular pressures being brought to bear in the capital and I think what's good about the operation we heard about is the Met taking that enforcement lead on the gang that they know about that's working beyond their boundaries."
Mr Thompson said police had made progress with organised gang crime over recent years.
"I wouldn't minimise that there are still clearly risks around gun and knife crime we want to work harder on," he said. "But if you think back over the last 10 years, with the headlines about young people being victims of gun and knife crime, those issues still happen but I think actually there's a significant success so far."
l Prince Freddie Gibbons, 29, and Antonia Ottely, 24, appeared on petition at Edinburgh Sheriff Court yesterday charged with being concerned in the supply of drugs. No plea or declaration was made on their behalf and the case was continued for further inquiry.
Mr Ottely was bailed and Mr Gibbons was remanded in custody.