Claims tuna in pet food linked to slavery and aggressive fishing

A team of six Greenpeace activists locked themselves to a truck to block access to the Mars Petcare factory in Whanganui this morning.

Campaigner Kate Simcock said six "passionate activists" were chained to the truck, which was set up to stop other trucks coming through.

"We believe that Mars relies on a constant flow of tuna and other raw products," Ms Simcock said.

She said the protest was against tuna from Thai Union being used in cat food pouches.

Thai Union used "really aggressive" and "destructive" fishing practices and had been linked to "slavery scandals" on their fishing boats.

Ms Simcock said the activists would remain in place "until we're really sure Mars has got the message".

They were also hanging a banner saying "Stop bad tuna" from the paws of the two billboard cats.

Activists hang a banner on the Mars Petcare building. Photo/ Stuart Munro

Two other cats painted on the factory were holding Greenpeace signs.

Ms Simcock said they were making the cats into "cativists".

Greenpeace are campaigning against Thai Union globally.

Ms Simcock said there was an meeting between Mars and Thai Union in the United Kingdom at 8pm New Zealand time.

The action hopes to influence the meeting.

The Greenpeace truck was blocking access to the factory.

Police had been to the site but had not taken any action. A Police spokesperson they were aware of the protest and were monitoring it.