Walkers has said a scheme to recycle its plastic crisp packets is not a publicity stunt but a genuine attempt to address environmental concerns.

The company launched the initiative after a social media campaign titled #PacketInWalkers urged the company to make its packaging recyclable. Consumers published pictures of themselves online posting empty crisp packets addressed to Walkers, forcing Royal Mail to urge protesters to put the packets in an envelope before posting them.

Walkers said it was unable to switch to recyclable packets until at least 2025. On Monday, however, it launched what it claimed was the first nationwide crisp packet recycling scheme, part of a collaboration with a US firm that specialises in reusing hard-to-recycle material.

Consumers will be asked to send their empty crisp bags to TerraCycle, which will shred them into plastic pellets to be used in items such as outdoor furniture and trays.

The environmental campaign group 38 Degrees organised a a petition signed by more than 333,000 people urging Walkers to switch to recyclable packets. Its executive director, David Babbs, said: “The public will be watching to make sure the new recycling scheme isn’t just a PR stunt.”

A spokesman from Walkers’ owner, Pepisco, said the initiative was not just a cynical exercise. Speaking to Sky News, Duncan Gordon said: “We have heard from our consumers. Yes, we have acknowledged there was a campaign of people posting in their crisp packets.

“We’ve heard that people really want to get involved and they are very passionate around this issue. We really want to do something about the environmental impact of our packaging.”

He said while Walkers’ plastic packets were “technically recyclable”, recycling firms did not accept them. Gordon said: “It is difficult to separate and collect them and it is is difficult to reuse that material. That’s why we are forming a partnership with TerraCycle, who specialise in recycling very difficult to recycle items, to launch this new recycling scheme.”

He confirmed that Walkers had pledged to make all its packaging recyclable, biodegradable or compostable by 2025. Asked why it would take so long, Gordon said: “It is a really difficult challenge to crack. We are investing millions of pounds with an expert team here in the UK and around the world to develop the next version of our crisp packaging.”

The environment secretary has also backed the scheme. “As the custodians of our planet, we must take action now to protect our oceans and wildlife from single-use plastic pollution,” Michael Gove said. “Walkers are setting a fine example with this new scheme, and I want to see other companies step up, follow suit and reduce their environmental impact.”

Walkers is urging customers to collect a batch of packets and drop them off at a collection points run by volunteers – but with only 191 participating collection points in the UK it could be a long journey for some.

For example, someone living in Hay-on-Wye, near the Welsh border, would need to travel more than 40 miles by car to get to the closest drop-off location near Caerphilly.

A courier could be arranged for free but Gordon urged consumers to use the service wisely. “We are conscious about the overall environmental impact. We would rather people get together lots of crisp packets rather than just sending in one or two,” he said.