Police have arrested 35 people and seized more than $1million in assets as part of a major meth bust in Wellington.

Six children were also located at the addresses searched in the operation.

Detective Inspector Darrin Thomson said the kids had been referred to Oranga Tamariki.

The investigation, which has been running since August 2018, has targeted two syndicates believed to have distributed millions of dollars of methamphetamine in the Wellington area.

A significant amount of those involved were King Cobra gang members in Porirua, police said.

Expensive artwork was also seized by police, who believe the offenders purchased to launder the drug money.

Seven firearms - including two military-style semi automatic weapons - were seized as part of the drug bust. Police say some were loaded when they carried out search warrants.

In total 31 men and four women, aged 23 to 42, have been arrested after raids in the Wellington and Central districts.

More than 200 charges are to be laid including distribution of meth and cannabis, money laundering and firearms offences.

Detective Senior Sergeant Tim Leitch with drugs, firearms, money and others items. Photo / Mark Mitchell

Seven firearms, including semi-automatic rifles, were shown to media alongside the large bags of methamphetamine and cannabis seized during the raids.

Gold jewellery, watches and large sums of cash were also seized.

More than 100 police were involved in the investigation.

The majority of the alleged offending has been in Porirua, Wellington City and Hutt Valley, according to police.

More than 40 search warrants have been executed with police seizing methamphetamine, cannabis, cash, vehicles, a launch, artwork, jewellery, gold and seven firearms.

The Police Asset Recovery Unit restrained assets valued at more than $1.1m. Police said the "social cost" of the meth seized equated to more than $4.3m.

Thomson, of the Wellington Drugs and Organised Crime team, said the hard work of officers would have "seriously disrupted" the commercial drug operations of the syndicates across Wellington.