TOKYO, May 10 (Reuters) - Leaders of seven of the world's richest nations meet next week at the G7 summit in the Japanese city of Hiroshima to discuss geopolitical, economic and climate issues as the war in Ukraine drags on and tensions rise between China and the United States.

WHAT IS THE G7 SUMMIT?

The G7 is an informal grouping of wealthy Western nations. It has no permanent secretariat or legal status. Each year, a different member country assumes the presidency of the group, sets priorities and organises a leaders' summit and ministerial meetings throughout the year.

Italy will take over the presidency from Japan in 2024. Russia was included in what became the G8 in 1997 but was suspended in 2014 after annexing Crimea from Ukraine.

WHEN AND WHERE IS IT?

This year's meeting will be held from May 19-21 in Hiroshima, Japan, which in 1945 was the first city to be bombed with an atomic weapon.

WHO IS ATTENDING?

The G7 comprises the United States, Britain, Canada, France, Germany, Italy and Japan. Representatives from the European Union also attend.

In recent years it has become customary to invite other nations to help bring to the fore key topics.

This year, the leaders of Australia, Brazil, Comoros for the African Union, Cook Islands for the Pacific Forum, India, Indonesia, South Korea and Vietnam are among those invited.

The G7 and other Western states are seeking to shore up alliances, reach out to the Global South and defend their shrinking influence as China and Russia make economic inroads and push an alternative to the existing international order.

HOW LONG HAS THE G7 BEEN AROUND?

The G7 was founded following the 1973 OPEC oil embargo as a forum for the richest nations to discuss global economic issues. Its countries have a combined annual GDP of $40 trillion - just under half the world economy.

FROM RUSSIA, CHINA TO NUCLEAR: WHAT'S ON THE AGENDA?

The G7 will hold broad discussions on climate change, the health of the global economy, inflation and global food security as they assess the impact of the Ukraine war.

SUPPORTING UKRAINE

More than a year after Russia invaded Ukraine, the conflict will take centre stage.

The G7 will want to show unity ahead of a likely Ukraine counter-offensive, underscoring the need for more weapons deliveries, political support and financial assistance. How much help the G7 is willing to provide in the coming months will play a large part in determining how the conflict pans out.

That will be coupled with promises to intensify sanctions, and in the immediate term a focus on forcing countries which help Moscow circumvent sanctions to comply with them.