US Secretary of State John Kerry said Sunday there was "no question" the Iran nuclear deal will make the Middle East safer if implemented, as he sought to win over sceptical allies.

"There can be absolutely no question that if the Vienna plan is fully implemented, it will make Egypt and all the countries of this region safer than they otherwise would be or were," Kerry told a Cairo press conference on the first leg of a mini-tour to sell the agreement.

"The United States and Egypt recognise that Iran is engaged in destabilising activities in the region –- and that is why it is so important to ensure that Iran’s nuclear programme remains wholly peaceful," he said.