World leaders have been urged keep a promise to the millions of people who died during Covid – by finalising an agreement on how to deal with future pandemics.

As a G7 summit begins in France, Dr Tedros Adhanom Ghebreyesus, director general of the World Health Organization, and Brazil’s president, Luiz Inácio Lula da Silva, have issued a joint letter saying a treaty needs urgent political backing at the highest level because “the next pandemic will not wait for us”.

The letter comes amid a rapidly expanding Ebola outbreak in the Democratic Republic of the Congo that already has 782 confirmed cases and 181 deaths.

Negotiators will meet next month for a new round of talks on the “pathogen access and benefit sharing” annexe to the WHO pandemic agreement.

The annexe must be in place before the agreement can come into effect, but countries missed a May deadline, unable to agree on how to share information on pathogens that could cause pandemics, and what access to vaccines, tests and treatments nations should be guaranteed in return.

Developing countries fear that if it is not mandatory for pharmaceutical companies to share products created after countries have shared their data on viruses and bacteria, then there could simply be a repeat of the Covid-19 pandemic when poorer nations were the last to receive vaccines.

Industry representatives argue that mandatory requirements could stifle research and development.

World leaders first announced plans for a pandemic treaty in March 2021. Five years on, Tedros and Lula told leaders: “the world must finish what it started, and … you can help it do so”.

They said they should bear in mind “a memory the whole world shares”, when hospitals overflowed and “families said goodbye to the people they loved through glass, or by telephone, or not at all”.

The letter added: “Estimates from WHO and others put the lives lost at up to 20 million. Humanity promised itself, in the rawness of that grief, that it would not face such a day again unprepared.”

The annexe is “the last piece of the puzzle” in order to keep that promise, they said. It will need “political will at the highest level”, “a spirit of equity” and “a sense of urgency”.

Covid also cost economies more than $13tn (£9.6tn), they said: “Against that, the investment in a system that catches an outbreak early is small.”