British Prime Minister Boris Johnson on Saturday acclaimed a "historic" action plan by G7 nations to prevent future pandemics, after Covid-19 wrecked economies and claimed millions of lives around the world.

The "Carbis Bay Declaration" -- named after the seaside town in Cornwall, southwest England, where world leaders are currently holding their summit -- comprises a series of health policy commitments. 

The collective steps include slashing the time taken to develop and license vaccines, treatments and diagnostics for any future disease to under 100 days, while reinforcing global surveillance networks.

It will be formally published Sunday, alongside the G7's final communique

"The #CarbisBayDeclaration marks a proud and historic moment for us all," Johnson said on Twitter, as world leaders kicked off the second day of their three-day summit. 

"Under this agreement, the world's leading democracies will commit to preventing a global pandemic from ever happening again, ensuring the devastation caused by COVID-19 is never repeated."

As part of the pact the G7 will boost genomic sequencing capacity, and support reforms to strengthen the World Health Organization (WHO).

Meanwhile, Britain says it will establish a new centre to develop vaccines to prevent zoonotic diseases spreading from animals to humans.

Johnson will also urge G7 allies to support plans for a global "pandemic radar" to identify emerging Covid-19 variants and track new diseases around the world.