Police were astounded when a man claiming to be a methamphetamine dealer walked into the New Plymouth station and handed over his stash yesterday.

Leith Castle, 36, arrived at the station just before 5pm with ten $200 bags of the class A drug, a glass pipe used to smoke it, two bags of cannabis and gave it to Detective Sergeant Greg Gray, head of the CIB drug squad.

Earlier in the day Mr Castle, who was fidgety and rocked uncontrollably during the whole process, contacted the Taranaki Daily News and asked a photographer and reporter to accompany him and to record what he was doing.

"I want it recognised so it doesn't just get taken off me and I get thrown out of the door," he said.

"I've got to be the craziest person in the country."

A surprised Mr Gray, who said he had no idea what was going on, took Mr Castle into an interview room and asked him what he wanted to happen.

"I want to be arrested and I want this to go to court and I want witnesses to be called," Mr Castle said.

He admitted to smoking "impossible amounts" of meth over the years.

Mr Gray was stunned by the admissions.

"As strange as it is, we don't often have drug dealers come in and offer themselves up," he said.

"These are fairly drastic measures to take," Mr Gray said.

Mr Castle told the reporter he believed police had been following him hoping he would lead them to a big supplier.

"If I'm wrong then I'm wrong, but if I'm not then I'm right."

Earlier Mr Castle told the Taranaki Daily News he had bought the drugs in New Plymouth from people he suspected were undercover police officers.

He alleged undercover police were trying to use others, including prostitutes, to "get" to him and he wanted it to stop.

"I don't really care what happens to me. At the end of the day it will stop all of the kids getting screwed to get to me. It will get me off the scene so they can't try to get to me.

"This is the only way I could fight it. You can't fight the police on the street," Mr Castle said.

He asked Mr Gray to have the drugs tested as he believed they had been tampered with.

Mr Gray said he was happy to listen to any concerns Mr Castle had but did not want to do it in front of the media and we were asked to leave.

After police interviewed Mr Castle he was arrested and charged with possession of methamphetamine for supply.

He was in police custody overnight and will appear in the New Plymouth District Court today.

Mr Gray said he had never experienced such a situation in 22 years on the force.

"It is probably a little bit out of the ordinary for somebody to come in and admit what they are doing," he said.

Police will investigate Mr Castle's claims.

"There are aspects of Mr Castle's situation that he outlined to us in relation to his suppliers and we are conducting inquiries to verify those or otherwise," Mr Gary said.

Outside the police station the man who dropped Mr Castle off said he had been behaving the same way for years.

The man said he feared that Mr Castle would have been "rolled" if he had not handed himself in.

- © Fairfax NZ News