Britain's fourth largest grocer, which unlike rivals makes about 30 percent of the food it sells, said on Thursday it would work through all of its own brand products to identify, reduce and remove any unnecessary plastic packaging.

The supermarket industry is under pressure to act on plastic waste given growing concern from the public and lawmakers about its damaging impact on the environment.

Prime Minister Theresa May has pledged to eradicate avoidable plastic waste by 2042 as part of a "national plan of action".

In January, privately-owned Iceland became the first British supermarket to promise to eliminate plastic packaging from all of its own brand products and called on the industry to follow its lead.

The 491-store Morrisons, which trails market leader Tesco, Sainsbury's and Walmart's Asda by annual sales, said its own research found plastic reduction is the third most important issue to its customers.

It said black plastic trays used for fresh meat and fish will be phased out by the end of 2019, while customers will be allowed to use their own containers for produce purchased from its butcher and fishmonger counters.

Other measures include trialling the effect of removing plastic packaging from fruit and vegetables, with an aim to examine how plastic packaging, which helps keep food fresh, can be reduced without increasing food waste. Drinking water fountains will also be fitted into new stores.

Market leader Tesco has committed to making all packaging fully recyclable or compostable by 2025 and is targeting a halving of packaging weight by the same date compared to 2007 levels.

Sainsbury's has reduced its own brand packaging by 35 percent since 2005 and is targeting a 50 percent reduction by 2020.

Asda said in February it would use 10 percent less plastic in its own brand products over 12 months. It had already committed to making sure all own brand packaging is recyclable by 2025.

Environmental groups have welcomed the grocers' moves but have said they do not go far enough.

The government plans to ban the sale of plastic straws, drink stirrers and cotton buds, is consulting on how the tax system can be used to change consumers' behaviour and has pledged to invest to develop new, greener, products and processes.

It has, however, resisted a call by campaigners and lawmakers to impose a so-called "latte levy" on single-use coffee cups.

(Reporting by James Davey; Editing by Alexandra Hudson)