India, others won't support US if Iran deal fails: Kerry

Secretary of State John Kerry has warned the Congress that countries like India, China, and Japan – major customers of oil from Iran – would no longer side with the US if the historic Iranian nuclear deal is not approved by American lawmakers.

"It is an illusion for members of Congress to think that they can vote this plan down and then turn around and still persuade countries like China, Japan, South Korea, Turkey, India - Iran's major oil customers," Kerry said in yet another passionate plea on Iranian nuclear deal in Philadelphia.

"They ought to continue supporting the sanctions that are costing them billions of dollars every yearIJ That is not going to happen," Kerry said.

"And don't forget that the money that has been locked up as a result of sanctions is not sitting in some American bank under US control. The money is frozen and being held in escrow by countries with which Iran has commercial dealings," he said in his speech.

"We don't have that money. We can't control it. It is going to begin to be released, anyway, if we walk away from this agreement. Remember as well that the bulk of the funds Iran will receive are those that sanctions relief are already spoken for, and they are dwarfed by the country's unmet economic needs," he said.

Kerry's public speech yesterday came after he wrote a letter to members of the Congress on the need to pass the Iran nuclear deal.

Kerry warned that if this plan is voted down, the US cannot predict with certainty what Iran will do.

"But we do know what Iran says it will do, and that is begin again to expand its nuclear activities. And we know that the strict limitations Iran has accepted will no longer apply, because they will no longer be any agreement," he said.

"Iran will then feel free to begin operating thousands of other advanced and other centrifuges that would otherwise have been mothballed. They will be free to expand their stockpile of low enriched uranium, rebuild their stockpile, 20 per cent enriched uranium, free to move ahead with the production of weapons-grade plutonium. Free to go forward with weaponisation research," said the top American diplomat.

latest figures indicate that the Obama administration is inching towards support for the deal in the Senate.