Z Energy noticed an increase in the number of service station drive-offs over the past month, coinciding with record-high fuel prices for motorists. (File photo)

The rising value of petrol has sparked a lucrative black market where 300 litres of the stolen black gold buys about $450 of methamphetamine.

A rare insight into the street value of black market drugs has come courtesy of Porirua resident Christopher Ashley Tyacke.

The 34-year-old father-of-four has spoken out after his sentencing for a raft of petrol thefts which took place across the Wellington region between January and July.

CHARLOTTE CURD/STUFF The rising value of petrol has sparked a lucrative black market where 300 stolen litres buys about $450 of methamphetamine. (File photo)

He was a daily meth user before spending 67 days in custody.

READ MORE:

* Service station drive-offs increase as fuel prices soar to unprecedented levels

* Wellington service station attendants copping motorists' fury over petrol prices

* Government will rush through legislation to look into petrol price margins

* Gull New Zealand plans expansion into Wellington region

* Government points to rising margins as petrol closes in on $2.50 in main centres

He has agreed to speak out about the growing black market shortly after being ordered to complete nine months of home detention in Porirua District Court on October 19 on the condition his photograph was not published.

STUFF Lawyer Paul Surridge said his client, Christopher Tyacke, was moving on from drugs and aimed to get a job.

"It was just an easy way to get meth through swapping petrol, because petrol's gotten so dear."

The country's largest retail fuel chain, Z, confirmed there had been an increase in service station drive-offs this month, as drivers in Wellington and the South Island bear the brunt of 39 cents of increases between October 2017 to September this year.

Tyacke explained 300 litres of stolen petrol - roughly $700 worth of 91 octane - could fetch about one gram of meth on the black market.

HAMISH RUTHERFORD/STUFF A BP station near the Basin Reserve in Wellington, recently charging $2.489 per litre. (File photo)

While a gram was once worth about $1000, he said, the value had fallen to about $450.

"There's a big industry of it... It's almost like a pre-order thing."

He did not previously think it was a problem to steal it - all up he took about $4400 worth - because the product was coming from big international companies.

"It was an easy way to get it without screwing people overwithout ripping off families."

Some of the offending was done so he could visit his kids. Now he says he will never do it again.

In court, Tyacke told Judge James Johnston about how his time already spent in custody had given him "a good ground to focussing on getting my kids back".

"I've had a lot of time to think. I've just felt quite guilty for my kids really - being in custody."

His lawyer Paul Surridge said Tyacke was moving on from his drug-fuelled past and wanted to get a job.

Judge Johnston said Tyacke had serious alcohol and drug issues.