The conference will bring together government and business leaders to help jump-start the economic portion of the broader US peace initiative, which is also expected to include proposals for resolving thorny political issues at the heart of the decades-old Israeli-Palestinian conflict.

Trump has touted the coming plan as the "deal of the century" but Palestinian officials have rebuked the US effort, which they believe will be heavily biased in favour of Israel.

Trump's Middle East team, led by his son-in-law Jared Kushner and regional envoy Jason Greenblatt, appears intent on focusing initially on the potential economic benefits despite deep scepticism among experts that they can succeed where decades of US-backed efforts have failed.

"This will give hopefully the people in the region the potential to see what the economic opportunities could be if we can work out political issues that have held back the region for a long, long time," a senior Trump administration official said on Sunday.

The participants in the June 25-26 conference in Manama are expected to include representatives and business executives from Europe, the Middle East and Asia, the administration official said.

However, a second senior US official declined to say whether Israeli and Palestinian officials would take part.

US officials had said earlier the peace plan would be rolled out after the Muslim fasting month of Ramadan, which ends in early June.

But the announcement of the investors workshop appears to set the stage for a sequenced release of the plan, starting with the economic plan in late June and later, at some time not yet clear, the political proposals.

Australian Associated Press