A two-month long operation into an alleged drug dealing syndicate importing and distributing controlled drugs has ended with the seizure of $5 million in controlled drugs.

Thirty police officers executed seven search warrants across Wellington City on Friday.

Operation Skipjack is an investigation led by the Wellington Drugs and Organised Crime team into the importation and supply of the Class B controlled drug Gamma Butyrolactone (GBL) and the class C controlled drug Eutylone.

Street names for GBL include G, fantasy, rinse and liquid ecstasy. Eutylone is an Amphetamine Type Substance (ATS) and is being sold as ecstasy.

Police have identified 20 suspected importations of Eutylone and have today seized approximately 400 litres of GBL.

This has a combined street value of more than $5 million and a Social Harm Index cost of more than $30 million.

As a result of Friday's warrants, two Wellington men, aged 29 and 35, will appear in the Wellington District Court tomorrow charged with importing a Class B controlled drug, importing a Class C controlled drug, and possession for supply of a class B controlled drug.

Police are also investigating items that could be used for the manufacture of methamphetamine located at one of the addresses.

Detective Inspector Darrin Thomson says Friday's activities are the culmination of months of dedicated investigative work.

'We have been monitoring this syndicate's activity for a number of months collecting evidence of their alleged drug dealing activity.

"As a result, we have deployed investigators and specialist staff across Wellington City to gather further evidence and make arrests for this offending.

'Operation Skipjack will cause significant disruption in the illicit drug market and the seizure of such an enormous of quantity of GBL will certainly reduce and prevent the harm associated with this drug.

'We are sending a clear message to these people that if you are going to derive your income from drug activity that harms our communities, we will be using all the legislation available to disrupt that behaviour.”