The United States is evaluating what will be accomplished at a summit Saudi Arabia has called to address soaring global oil prices before a decision will be made on who will attend, a White House official said on Thursday.

'The president's first question is what are we going to try to accomplish,' US President George W Bush's national security adviser Stephen Hadley told reporters.

'Because if you're going to have a meeting like that, there's obviously going to be great expectations that something will come of it that will have an impact on oil prices to reduce them and stabilise markets,' he said.

Hadley declined to say whether Bush himself was open to attending the gathering on June 22 in Jeddah hosted by Opec's most influential member, Saudi Arabia.

'There are expectations that have been generated and it is important that those expectations not be unrealised because that in itself will have an effect on oil prices and the markets,' Hadley said.

He said that Bush was discussing the upcoming meeting with European leaders he was visiting on a weeklong farewell tour.

Meanwhile, Japan's energy minister said he would attend the meeting in Saudi Arabia while Prime Minister Yasuo Fukuda is 'studying' the possibility of going.

Japan is one of the world's largest importers of oil.

Economy, Trade and Industry Minister Akira Amari said Saudi Arabia had invited Fukuda to the summit 'The prime minister's office is studying' the possibility of Fukuda attending.