UPDATED 8.34PM Six tonnes of dairy sewage has been dumped in the middle of Wellington, in a protest by Greenpeace.

The cow urine and other dairy waste - sealed in eight heavy-duty tanks - have been placed across the two main entrances to ACC’s offices on Molesworth Street.

Greenpeace campaigner Kate Simcock said it's part of an escalating row over the government department’s link to the controversial Ruataniwha irrigation scheme in Hawke’s Bay.

"ACC looks set to invest millions of taxpayer dollars in the controversial Ruataniwha dam, which is going to pollute our rivers. So we've blockaded the doors of the ACC building in Wellington with six tonnes of dairy effluent.

"ACC cannot be spending millions of taxpayer dollars investing in something that's going to pollute our rivers through the expansion of further dairy."

Kate Simcock said they have no plans to leave until ACC gets the message.