TURIN -- Energy ministers from the Group of Seven wealthy countries meeting in Italy are discussing setting a common target date of 2035 to shut down their coal-powered power plants, a source close to the matter told Reuters on Monday.

An agreement on coal would mark a significant step in the direction indicated by the COP28 United Nations climate summit in Dubai last year to transition away from fossil fuels, of which coal is the most polluting.

Diplomatic negotiators for the G7 nations - Italy, the United States, Britain, France, Germany, Canada and Japan - discussed the issue until late on Sunday, with one country still opposing the move, said the source, who asked not to be named.

The energy ministers' meeting hosted by Italy, which holds the rotating G7 presidency this year, runs on Monday and Tuesday in the 17th century Venaria palace, a former royal residence outside Turin.

Demonstrators gathered in Turin on Sunday evening, setting fire to pictures of G7 leaders they say are not doing enough to fight climate change, and chanting slogans including "Them 7, us 99%".

As well as seeking a deal on ending coal in electricity generation, Rome also aims to spur efforts to develop battery storage capacity and boost investment in power grids, two sources said, as the G7 increases its renewable energy output.

The G7 bloc could indicate the need for a six-fold increase in battery capacity - critical to store renewable energy, which is intermittent - by 2030 from 2022 levels, one of the sources said.

Nuclear energy and biofuels are two other issues at the top of Italy's agenda for the meeting, and it wants to see both energy sources in the final communique among options G7 nations can pick to cut their use of fossil fuels in power generation and transport, the sources said,

The right-wing Italian government says nuclear energy should play a part in meeting the country's 2050 net-zero emissions target, even though nuclear power was rejected in a 2011 national referendum.

Energy Minister Gilberto Pichetto Fratin said on Sunday that Rome hoped to persuade the European Commission "to recognise that biofuels can significantly reduce (carbon dioxide) emissions from vehicles".

Italy's energy ministry declined to comment on the issues being negotiated at the Turin G7 meeting.