Under proposals set out by the prime minister, the 5p charge on plastic bags that has helped dramatically reduce their use could be doubled to 10p, and extended to small retailers and corner shops.
But it comes amid reports the chancellor is unhappy with the plans, with Treasury sources briefing against them.
Ms May and her chancellor found themselves at loggerheads after he highlighted the dangers of crashing out of the EU as Dominic Raab, the Brexit secretary, tried to convince the country the government is adequately prepared to do so.
The prime minister made the announcement on the plastic bag charge as she finished her African tour in Kenya, where she said six more countries had signed up to a Commonwealth drive to clean the oceans.
Ms May said: “We have taken huge strides to improve the environment, and the charge on plastic bags in supermarkets and big retailers has demonstrated the difference we can achieve by making small changes to our everyday habits.
“I want to leave a greener, healthier environment for future generations, but with plastic in the sea still set to treble we know we need to do more to better protect our oceans and eliminate this harmful waste.”
Theresa May dances with children on trip to South Africa
Currently only big retailers are affected by the 5p charge, which has seen plastic bag sales in England’s ‘big seven’ supermarkets drop by 86 per cent and 13 billion plastic bags taken out of circulation in the past two years.
The consultation, to be launched later this year, will explore the possibility of increasing the 5p minimum charge, potentially doubling it to at least 10p.
It will also ask whether to extend it to small- and medium-sized enterprises that are estimated to use more than three billion bags each year.
But a Treasury source said earlier this week that increasing the charge looks like “profiteering” and would leave consumers feeling “hammered”.
Mike Cherry, national chair of the Federation of Small Business, said most small businesses will back an increase in the levy, as long as they are given time and support to adapt.
He added: “It is important, however, that government stops short of introducing any type of reporting duties that would add unnecessary red tape for smaller firms.”
Theresa May visits Africa on trade trip – in pictures
Show all 39
Mr Hammond is also said to have opposed other plastic taxes backed by Downing Street.
If pushed through, the increase in the plastic bag charge will be the latest government move on the issue including a ban on microbeads that harm marine life, plans to ban the sale of plastic straws, stirrers and cotton buds, and introduce a deposit return scheme to drive up the recycling of drinks bottles and cans.
To spearhead further international collaboration, the prime minister also announced more than £61m in UK aid money to boost global research and help countries stop plastic waste from entering the oceans, at this year’s Commonwealth Heads of Government Meeting.
The UK will now provide £250,000 to support the design and delivery of a Sustainable Blue Economy Conference, in Kenya in November, while six African countries – Seychelles, Mauritius, Sierra Leone, Mozambique, Namibia and the Gambia – have now also joined the Commonwealth Clean Oceans Alliance (CCOA).
The UK will provide up to an additional £5m in funding to assist CCOA countries seeking to take action on plastics.
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies
Join our commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies