Tony Blair and Silvio Berlusconi have agreed on plans to increase aid to Africa and tackle climate change, they said after holding talks in Rome.
The pair said they were agreed on the G8 summit agenda
The UK and Italian prime ministers met as Mr Blair began a diplomatic offensive ahead of July's G8 summit.
Mr Berlusconi said they had "common views" on the G8 agenda. Mr Blair said the talks had been "constructive".
Pressing for a joint world aid plan, he argued Africa was the only continent to "go backwards" over the last 30 years.
This is the final phase of talks before the G8 industrialised nations meet at Gleneagles in Scotland. The UK is currently president of the G8 group and will chair the summit.
Mr Blair will also visit the US, Russia, France and Germany.
He will also hold talks via a video link with Canada and Japan.
The trip comes as environmentalists said an alleged leaked document showed real action on climate change was being blocked by the US.
EU development ministers this week agreed to double aid to poorer nations. Under the deal, the EU's aid will be worth an extra £14bn annually in five years' time.
Some Italian opposition politicians question whether the country's financial problems will mean its target will be hit.
But Mr Berlusconi said: "I have assured Mr Blair of my personal support and my country's support in favour of what I know is going to be a very reasonable, sound and viable set of proposals."
A five-mile cordon is being used to protect the G8 summit from protests
Mr Blair said Africa's plight had been on the G8 agenda for a long time but the new plans combined aid and debt with governance and conflict.
Mr Blair later joined rock star campaigner Bob Geldof for a seminar on Africa.
He told the seminar: "What's happening in Africa today is something that, if it happened in any other continent in the world, there would be outrage.
"It would be on our television screens every night and there would be immense sustained pressure on world leaders to act."
Mr Blair and Mr Berlusconi's talks also included Iraq, Afghanistan and the Middle East.
And the UK prime minister said the European economy had to modernise as it faced intense competition from countries like China and India.
The two leaders also discussed European Union funding - and are thought to have touched on the annual rebate the UK won for its contribution in 1984.
Mr Berlusconi said: "I think that at the end of the day one might also modify the current system with respect to rebates."
Climate change 'leak'
Earlier this month BBC News learned that the US Government was unlikely to accept Mr Blair's three-point plan for a new deal on climate change.
A document purporting to be a draft communique for the G8's climate change talks has now been published on the Carroll.org.uk weblog.
Downing Street refused to say whether or not the leak was genuine.
But Friends of the Earth said it showed the G8 was relying on a "failed recipe" instead of using radical solutions.
The document says climate change is a "serious long-term threat" which could affect the whole world and calls for "urgent action".
But it does not include specific targets or timetables for reducing greenhouse gases.