UK prime minister Theresa May and her environment minister Michael Gove are due to unveil a broadening of a ban on free plastic bags to tackle the UK's "throwaway culture", UK media reported on Wednesday (10 January).

A mandatory 5p charge on plastic bags will apply to all shops in England, including those with fewer than 250 employees who had been exempt from the rule until now.

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UK environment secretary Michael Gove has lamented his country's 'throwaway culture' (Photo: Policy Exchange)

May is expected to announce the lifting of the exemption on Thursday during a speech on the environment.

But while the news is framed as the Conservative government showing its greener side, other motives are at play as well.

What has gone mostly unreported in the UK is that the plastic bag charge is needed to fulfil a requirement in an EU directive.

In 2015, the UK government and its 27 European counterparts unanimously agreed to new pan-European rules on plastic bags.

A large majority of the European Parliament – 539 votes in favour, 51 against, 71 abstentions – also supported the directive.

The directive requires national governments to do at least one of two things: either ban shops from giving away free lightweight plastic bags, or to come up with other measures that will reduce plastic bag consumption drastically.

If member states choose the second option, they have to make sure that by the end of 2019, their citizens use no more than 90 such bags per year. By the end of 2025, plastic bag consumption per capita has to be down to 40.

On average EU citizens use around 200 plastic bags a year.

The deadline for putting in place the first option – charging plastic bags – is 31 December 2018.

Several member states introduced a mandatory surcharge on plastic bags as of 1 January 2018, including Greece, Italy, and Slovakia.

While the UK government's motives may be inspired by becoming "the first generation to leave the natural environment in a better state than we inherited", as quoted by government spokesmen on separate occasions, the EU angle is noticeable by absence.

The 2015 bill which introduced the 5p charge for shops with more than 250 employees does not even mention the EU or the directive, unlike transposition bills in other EU countries.

Then again, environment secretary Michael Gove, a major figurehead for the Leave campaign, may want to portray the success of the 5p charge as a domestic affair.

Since the ban was in place, single-use plastic bags consumption has dropped by almost 90 percent.