A major producer of plastic bottles in the UK is to increase its recycled content to more than 50% within four months.

Princes, which produces 7% of plastic bottles used in the UK, says it has started the process to increase the amount of recycled plastic in all its bottles and will finish by September.

The company is a major producer of plastic bottles for drinks and oils, averaging 900m plastic bottles each year for its own brand and other retailers in the UK.

David McDiarmid, corporate relations director for Princes, said: “We want to increase the recycled content of all the plastic we use and have been working for some time to implement 51% RPET [recycled plastic].

“This is a significant step for not only ourselves, but the wider grocery industry too as we will reach millions of households through our supply of brands and customer own-brand soft drinks and oils.”

McDiarmid said the company wanted to commit to 100% recycled plastic in all its products “as soon as we can”.

The company said it was sourcing recycled material from a UK supplier.

Major producers of plastic bottles have traditionally lagged behind “green” companies in the drive to use more recycled plastic. The Belgian company Ecover rolled out a 100% recycled plastic washing-up bottle earlier this year. The company has pledged to have 100% recycled plastic in all its household products by 2020.

On Tuesday, Iceland became one of the first supermarkets to announce it was to use a new labelling system to allow consumers to avoid plastic packaging.

It is hoped the new plastic-free “trust mark”, launched by the campaign group A Plastic Planet, will be prominently displayed on food and drink products, and will be taken up by other major supermarkets.

As well as items obviously wrapped in plastic, scores of everyday products – from tinned beans to tea bags – have some plastic in their packaging.

Plastic pollution is now so widespread that it has been found in tap water, fish and sea salt – with unknown consequences for human health.

Earlier this year the Guardian revealed that supermarkets are responsible for 1m tonnes of plastic waste a year.