Two graffiti gangs are pushing up train ticket prices as rail companies pay out millions of pounds to repair vandalised carriages.

British Transport Police has identified two groups of taggers, totalling about 12 people, who are causing chaos to train services across Sussex.

South Central, which operates Brighton station, will spend about £3 million this year to clean the paint off its carriages and loses up to £20,000 for each rush-hour train forced out of service.

As part of The Argus campaign Tell On Taggers, we are printing the tags of the gangs in the hope they will be named by members of the public.

Police say the most troublesome is the NT tag, which has been found on carriages on the north-south line stretching from Gatwick to Brighton. The tag is frequently found alongside others including SPC, PHAR, FRY AND CREL.

The second gang is led by the DMC tag, which is believed to be the calling card of the group rather than an individual. It is often found with the MOOD and TM tags in the Worthing area.

PC Sarah Burfoot, based at Brighton station, is leading the fight against graffiti on the county's trains.

She has compiled files on each of the taggers, taking photographs of their handiwork wherever it appears.

She said: "These people may well be frustrated artists but what they are doing is sheer vandalism. Their handiwork may look nice to them but they are committing a serious crime.

"I definitely support The Argus campaign. Any information we can get to stop people doing this will be gratefully received."

PC Burfoot, who has been in post for two years, explained NT can stand for a variety of things, most commonly Network Terror or New Team.

DMC is believed to be linked to Durrington, with many of the tags signed off by Durrington Army.

The initials stand for Durrington Murder Charge or Durrington Means Crime.

PC Burfoot added: "Wandering on to a train line is very dangerous. They are playing with death when they play with trains. That may be part of the appeal.

"Maybe it would help if there were more areas for these people to do graffiti legally but I don't think a lot of them would get their kicks from that."

A South Central spokesman said paying to clean up the graffiti will affect prices.

He said: "In the long term, as the costs for cleaning accumulate, this problem will have an effect on ticket prices."

PC Burfoot is working with the graffiti squad based on London Underground, which uses a handwriting expert to prove whether or not the most well known tags are done by the same person.

She also collects spray cans left behind by taggers and sends them for fingerprint analysis.

She said: "Once we have a suspect we will have powers to search their home. A lot of taggers take pictures of their work because they are proud of it, so we seize cameras. We also take computers and text books, if they are younger."

This evidence can be used to prosecute taggers for dozens of offences and could see them given jail sentences of up to ten years.

Anyone who recognises a tag should call The Argus on 01273 544517, the city council's specialist team on 01273 294514 or Crimestoppers anonymously on 0800 555111.