Heavily armed police have raided four properties linked to an outlaw motorcycle gang in Melbourne's north this morning.

A senior member of the Nomad chapter of the Hell's Angels is in custody following the raids in Thomastown, Greensborough and Bundoora about 8am today.

Police are believed to have blasted their way into a heavily fortified property in Thomastown, believed to be the headquarters of the Nomad chapter.

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A Hell's Angels warehouse in Thomastown. Photo: File photo
"We were required to force entry to those premises. I can't really go into detail as to how we did it," Superintendent Doug Fryer told radio 3AW today.

"This is part of our ongoing focus around outlaw motorcycle gang criminality and certainly Victoria Police is continuing to take affirmative action to prevent, detect and disrupt organised criminality among OMCG clubs, an we will continue to do so."

Police are still searching the properties this morning.