Fuel thefts are rising across the country, with two men appearing in court following separate early-morning incidents that police say highlight a growing trend.

In Christchurch, officers were called to Sockburn about 4am after reports of a person attempting to siphon petrol from a vehicle.

While making inquiries nearby, police stopped a vehicle.

A search uncovered five 60-litre containers, a battery-operated siphoning pump, and a small amount of methamphetamine.

A 31-year-old man is due to appear in the Christchurch District Court today, facing charges of unlawfully interfering with a motor vehicle, possessing equipment capable of facilitating dishonesty offending, and possession of methamphetamine.

Just 20 minutes later and more than 900km away, police in Hamilton were responding to another fuel theft.

At about 4.20am, a man was spotted on a live camera siphoning diesel from his own worksite in Peacocke.

He fled in a hatchback but was intercepted by police south of the city around 4.35am and arrested.

Officers located three containers filled with diesel inside the vehicle, along with tools, drugs, and knives.

The 35-year-old man is expected to appear in the Hamilton District Court today, though his charges had yet to be confirmed.

Assistant Commissioner Tusha Penny said the cases reflected a wider rise in diesel thefts.

“These incidents are an example of where we are reliant on sharp-eyed members of the public to call police immediately when they see any suspicious activity,” Penny said.

“We want to thank the community for working with us to ensure these offenders were arrested and will be held to account.”

It comes as motorists using diesel are being warned to expect to see its price lift over $4 a litre this week.

Z issued a national list price advisory for commercial customers, effective Tuesday, noting that diesel will lift 55c a litre.

That would put the price at service stations to $4.16 a litre