The G8 summit in Germany brings together world leaders from the leading industrial countries for a three-day meeting. The summit is taking place amid growing tension with Russia over nuclear weapons and the US over climate change. Here is a guide to the G8 and some of the key issues that will be discussed.
Reducing global warming is likely to be high on the G8 agenda
WHAT IS THE G8?
The G8 is an informal group of the world's richest countries who meet every year to discuss issues of common concern.
Its eight members are the US, the UK, France, Germany, Japan, Italy and Canada, while Russia was added as a full participant in 1998.
The meetings began in 1975 after the oil crisis disrupted the world economy, but its agenda has gradually expanded to include political issues such as nuclear proliferation and terrorism.
The presidency of the G8 rotates each year. Russia hosted the 2006 meeting in St Petersburg, while next year it will be Japan's turn.
WHO WILL BE ATTENDING?
This year's G8 summit is hosted by German Chancellor Angela Merkel, and takes place between 6 and 8 June 2007 in the Baltic resort of Heiligendamm, the oldest seaside spa in Germany.
For UK Prime Minister Tony Blair, who is stepping down on 27 June, it will be his last summit, while for newly elected French President Nicolas Sarkozy it will be his first.
Also attending the meeting will be US President George W Bush, Russian President Vladimir Putin, Italian President Romano Prodi, Japanese Prime Minister Shinzo Abe, Canadian Prime Minister Stephen Harper and EU President Jose Manuel Barroso.
Key leaders from major developing countries, as well as several African heads of state, have been invited to attend as observers, as have leaders of international organisations such as the UN and the International Monetary Fund - but not the outgoing president of the World Bank, Paul Wolfowitz, who is stepping down after allegations of favouritism.
The most controversial issue at the summit is likely to be climate change.
Germany and other European governments are pressing for a new treaty to replace the Kyoto agreement - which expires in 2012 - with stricter limits on greenhouse gas emissions.
Germany has proposed a 50% cut in greenhouse gas emissions by 2050 and wants a 20% improvement in energy efficiency by 2020, something the EU has already supported in principle.
The US, which has not ratified the Kyoto Treaty, is opposed to mandatory targets and has reportedly blocked any mention of such figures in the final communiqué.
Instead, US President George W Bush plans to host a meeting of the world's 14 biggest emitters of greenhouse gases to in order to agree long-term goals and share environmental technology - with a deadline of the end of 2008, the time at which he will leave office.
But other leaders are opposed to Mr Bush's plan to go outside the UN system, while experts say his proposals lack teeth.
NUCLEAR WEAPONS IN EUROPE
President Putin's threat to target missiles at European cities if the US goes ahead with the deployment of an anti-ballistic system in East European countries may unexpectedly dominate the G8 summit.
The Russians have long been unhappy with US plans to install ballistic missile defence systems, believing it destabilises the arms race and weakens deterrence.
The US argues that it is targeting "rogue states" such as Iran and North Korea, not the Russian nuclear arsenal, with its interceptor missiles and radar systems.
The Russians were particularly angry that they were not notified about the deployment of the system so near to their borders in Poland and the Czech Republic, states which were once part of their Soviet-era sphere of influence in the Warsaw Pact.
POVERTY IN AFRICA
Two years ago, at the Gleneagles G8 summit in Scotland, world leaders promised to double aid to Africa in order to tackle global poverty.
So far, these promises have not been met.
However, boosted by higher prices for raw materials, African economic growth has been stronger than expected.
Now Germany wants the G8 to boost private investment in Africa, as well as spending more money to tackle the HIV/Aids crisis.
It is also proposing a micro-credit fund for Africa to offer loans to small entrepreneurs who want to start a business.
GLOBALISATION AND TRADE
German plans to use the G8 summit to find a more socially equitable form of globalisation are likely to run into opposition from the UK and the US.
Germany is the sole advocate of a plan to regulate hedge funds, which use money from wealthy private investors to take large stakes in companies and currencies.
And plans to regulate foreign exchange markets and stabilise currency fluctuations are also likely to make little headway.
However, leaders will express concern about the growing "global imbalances" (code for the huge US trade deficit) and hint that further currency realignment might be necessary.
And Germany will host a meeting of key trade ministers in Potsdam between 19 and 23 June, to try to revive the stalled Doha Round of world trade talks.
Russia is also likely to clash with other G8 countries on key regional issues.
On Kosovo, Russia opposes a plan to give the province effective independence from Serbia, after years during which it has been governed by the UN and protected by a Nato-led peacekeeping force.
Russia also opposes tougher sanctions against Iran to force it to abandon its nuclear enrichment programme, after criticism by the International Atomic Energy Agency and Western nations.
On the Middle East, little progress is expected on resuming the stalled peace talks, but leaders may discuss resuming financial aid to the beleaguered Palestinian administration.
And US hopes for more help from other G8 countries in fighting terrorism, and in particular putting more troops and resources in Afghanistan and Iraq, are likely to meet with a lukewarm response.