"Can regional co-operation be translated into a political solution? Can we achieve prosperity for Palestinians, Israelis and Jordanians while the Israeli occupation continues?
"Any plans will be meaningless without progress in the peace process," he said.
Erekat also urged Israel to take immediate steps to show its commitment to economic co-operation, such as giving Palestinians in the West Bank more control over water resources.
"We can't dig wells without permission from the Israelis and have to buy water to give to refugee camps," he said.
"Israel deciding to give back water to the Palestinians - it's such steps that are urgently required."
An Israeli foreign ministry official said that while his country was committed to Japan's initiative, it also prioritised bringing security to the region over economic development.
"As long as lawlessness continues and terrorists continue to launch missiles, security will unfortunately remain the critical factor," said Haim Divon, deputy head of the ministry's international co-operation division.
Under the Japanese initiative unveiled on Wednesday, the agro-industrial park will be built near the town of Jericho and process agricultural products from the occupied Palestinian territories like oranges and tomatoes.
Finished products will be shipped to Jordan, Israel will be responsible for the park's security and will share technical expertise and the park is expected to employ Palestinian workers.
The Jordanian delegate stressed the importance of revitalising a Palestinian economy depressed by years of conflict.
Farouk Kasrawi, special adviser to Jordan's King Abdullah II, pointing to high unemployment and an ailing economy, said: "With a better economy, the local people will be more open to reconciliation.
"This economic process should be a building block for a viable economy for Palestine - an essential step in state building."
Tokyo is set to dispatch a research team later this month to select possible sites for the park and the four parties are set to start working-level talks on the initiative in June.