Ministers are looking at proposals to use more of Britain's overseas aid budget to cut plastic pollution of the oceans, Downing Street had indicated.
Environment Secretary Michael Gove is reportedly pressing the Department for International Development to divert more of its budget to tackling the problem.
He is said to have highlighted the issue after researchers in Germany found 90% of the plastic entering the oceans comes from just 10 rivers in Asia and Africa.
The Prime Minister's official spokesman confirmed that Mr Gove was working with International Development Secretary Penny Mordaunt to see what more the Government could do to deal with the problem.
"The Government is a global leader in protecting oceans and marine life and we have already taken significant steps to tackle plastic waste," the spokesman said.
"Michael Gove and Penny Mordaunt are actively looking at what more we can do in this specific area.
"Their departments have a strong record of work on the environment and development and tackling marine pollution is a good example of where we can apply the Government's joint strengths."
The move comes amid heightened awareness of the effect of pollution following the BBC's Blue Planet II series.
According to the Helmholtz Centre for Environmental Research, 90% of the plastic waste entering the oceans comes from the Nile and the Niger rivers in Africa, and the Yangtze, Yellow, Haihe, Pearl, Mekong, Amur, Ganges and Indus in Asia.
The Prime Minister's spokesman said the Government has already committed £5.8bn to environmental protection and tackling climate change in developing countries between 2016 and 2021.
Attending a climate change summit in Paris, Theresa May has announced a further £140m to help the world's poorest communities build resilience to extreme weather events caused by global warming.