Economic plan 'necessary pre-condition' for Middle East peace: Kushner

White House adviser Jared Kushner said on Tuesday that his plan for the Middle East was "the opportunity of the century" for the Palestinians but that their acceptance was a pre-condition to peace.

"Agreeing on an economic pathway forward is a necessary pre-condition to resolving the previously unsolvable political issues," Kushner said as he opened a workshop in Bahrain being boycotted by the Palestinian Authority.

While the two-day meeting will not address political solutions in the Middle East, Kushner acknowledged the need to take them up later.

"To be clear, economic growth and prosperity for the Palestinian people are not possible without an enduring and fair political solution to the conflict -- one that guarantees Israel's security and respects the dignity of the Palestinian people."

Kushner acknowledged widespread scepticism about the intentions of President Donald Trump, his father-in-law, who has taken an unapologetically pro-Israel line including recognition of Jerusalem as Israel's capital. 

But Kushner said that the Palestinians have been ill-served by previous peace-making efforts. 

"My direct message to the Palestinian people is that despite what those who have let you down in the past say, President Trump and America have not given up on you," he said. 

He dismissed the mocking description of his peace plan as the "deal of the century" but said: "This effort is better referred to as the opportunity of the century, if the leadership has the courage to pursue it."

The economic plan, revealed by the White House on Saturday, calls for $50 billion in investment over 10 years in the Palestinian territories and their Arab neighbours.