Three 20 litre drums of unknown chemicals have been dumped at a North Shore cemetery and polilce are warning people to stay away.

Fire service spokesman Colin Underdown said they were called by police about 9.40am after a council staff member noticed the drums dumped down a bank at the Birkenhead-Glenfield Cemetery.

Underwood said they were unsure what chemical was inside the drums, two of which were full and sealed.

The third was empty and had been tipped out.

"We don't know what quantity of the chemical was tipped out, but they're 20 litre containers so that would be the maximum."

Underdown said the fire service had cordoned off the area and the council would arrange for the drums to be removed and the spill cleaned up.

Police are investigating how the drums got there and who was responsible, he said.

The public is advised to avoid the cemetery.

Meanwhile, the fire service was also called to help clean up a fuel spill on the northwestern motorway this morning.

A truck spilt fuel on the city bound lane between the Te Atatu and Patiki Rd exits around 11.20am.

Underwood said he understood the spill was the result of the truck's drive shaft coming loose and smashing into its fuel tank.

The fire service's salvage team had mopped up the fuel and was being helped by a contracted motorways clean-up team.

- © Fairfax NZ News