Police have seized cars, cash, synthetic drugs and hundreds of thousands of dollars worth of methamphetamine in a series of armed raids in Christchurch.

Detective Sergeant Phillip Sparks said members of the police's offender taskforce searched several properties across the city, including a motel in Riccarton, as they "exposed a methamphetamine supply ring" on Wednesday.

They seized an estimated 500 grams of methamphetamine, synthetic drugs, more than $100,000 cash, four cars and a loaded pistol, Sparks said.

SUPPLIED A man is arrested by police on Riccarton Rd.

Three people were expected to appear in the Christchurch District Court on meth-related charges on Thursday.

"The police are going to continue to intervene in these criminal groups dealing methamphetamine and disrupting the flow on effects that the drug has on crime."

Bernard Wong was driving to get some lunch when he saw several members of the Armed Offenders Squad on Riccarton Rd.

He said a police officer asked him to stop driving.

"One [police officer] pointed a gun at a silver parked car on the curb. They dragged the driver out and apprehended him.

"Then I saw three police officers dash into a Kiwibank."

Wong said another man was arrested outside.

The offender taskforce, a group set up to target high profile criminals in Canterbury, has seized millions of dollars worth of drugs, large sums of cash and 128 illicit firearms since February.