(CNN) - The UK's postal service is urging environmental campaigners to stop sending empty potato chip bags without an envelope after the launch of a campaign urging the country's most popular chip producer to ditch its plastic packaging.
The online campaign, which has been signed by more than 310,000 people, calls on the PepsiCo-owned British chip manufacturer Walkers to make its plastic packaging more environmentally friendly.
Campaigners have been posting pictures of themselves mailing their empty bags of chips, or crisps as they are known in the UK, through the Royal Mail with the hashtag #PacketInWalkers.
The UK consumes approximately 6 billion packets of potato chips every year, according to campaign organizer Geraint Ashcroft. Most of those bags are not recyclable.
"That's an awful lot of landfill and poison for the environment," Ashcroft wrote on the campaign's petition page.
Walkers, which produces 11 million bags of potato chips daily, has said that it plans to make its packaging plastic-free by 2025.
In a statement emailed to CNN on Wednesday, a Walkers spokesperson said: "We have received some returned packets and recognize the efforts being made to bring the issue of packaging waste to our attention. The returned packets will be used in our research, as we work towards our commitment of improving the recyclability of our packaging."
The spokesperson added that PepsiCo is working on a number of ways to tackle the issue, including a pilot of compostable packaging in the U.S., India and Chile.
But some campaigners say those proposals aren't enough.
Campaigner Jarred Livesey wrote on Twitter: "2025 is too long to wait for you to use plastic-free packaging. It's just not good enough. You produce 4 billion packs per year. I'm sending these back to you so you can deal with your own waste. #PacketInWalkers."
Some, however, have hinted it might be more environmentally -- and physically -- friendly to ditch their potato chip habit altogether.
"What if - instead of buying crisps and posting the packages back to @walkers_crisps - we just save our planet AND cholesterol levels by not buying crisps...," Lisa Ann Pasquale wrote on Twitter.
According to UK law, the Royal Mail must treat the potato chip bags as mail as long as they're properly addressed. Since Walkers has a registered Freepost address, any correspondence to the company doesn't require customers to pay for a stamp.
"If an item is addressed properly and carries the correct postage then Royal Mail is obliged by law to handle and deliver the item to the stated address," a Royal Mail spokesperson said in a statement emailed to CNN.
The national mail service has said, however, that it "strongly encourage(s)" activists involved in the campaign to use an envelope.
"If they are taking part in this campaign we would urge them to put crisp packets in an envelope before posting," the statement said, adding that customers who don't properly package their bags could cause delays or be taken out of the system altogether.
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