Four men have admitted running an international paedophile ring that distributed millions of indecent images and films of children to over 40 countries around the world.

Ian Frost, 35, and his partner Paul Rowlands, 34, Frost's brother Paul, 37, and 32-year-old Ian Sambridge have pleaded guilty at Nottingham Crown Court to various charges of making, distributing and possessing indecent images of children.

The force said smashing the ring had resulted in 132 children in the UK being protected and safeguarded, and a number of paedophiles being taken out of positions of trust, including teachers, doctors, youth workers and police officers.

The group had been involved in the running of illegal uncensored news groups on the internet in order to circulate the images and movies to 46 countries across the globe, Lincolnshire Police said.

At a briefing ahead of the court hearing, Detective Superintendent Paul Gibson, of Lincolnshire Police, said officers first received intelligence from German Federal Police in November 2005 that Ian Frost was running a news service that had an association with indecent images of children. Officers executed a search warrant at Frost's home in 2006 in the small picturesque hamlet of Martin Dales in Woodhall Spa, Lincolnshire, which he shared with Rowlands.

Police found a piece of equipment Det Supt Gibson called a "raid array" - a redundant array of independent disks - which is made up of a number of hard drives wired together. Officers found the raid array had been operating an uncensored news service in Manhattan, New York, in 2005 before moving to the location in Lincolnshire.

Det Supt Gibson said illegal news services, which are legal if censored, were "unique" because they operate like a virtual noticeboard containing folders of particular interest that can be shared around the world because linked news servers talk to one another and share information.

IT workers Ian Frost and Rowlands, he said, were running a news service called Athenanews which allowed users to pay a fee depending on the amount of download they required, upon which they were issued with a username and password, and could then search for desired content.

Officers also found other news services were being run by Paul Frost, also an IT worker, from Woodhouse in Sheffield, South Yorkshire. Sambridge, a legal adviser, was running another news service from a location in St Albans, Hertfordshire.

The extent of the images and films uncovered by officers ranged from the lowest level of indecent images of children to the most extreme, Det Supt Gibson said.