London: The United States took a “fundamental decision” to exclude Saudi Arabia from its diplomacy towards Iran — and the outcome served the kingdom’s best “interests”, a senior US State Department official has said.

Secret talks between the US and Iran preceded last month’s agreement in Geneva, which imposed formal limits on Tehran’s nuclear programme. The covert meetings, mediated by Oman, began when Hassan Rouhani took office as Iran’s president in August.

The US deliberately kept Saudi Arabia and its other Gulf allies in the dark. Saudi Arabia, a rival of Iran, has vented its fury over being shut out and accused the US of endangering the “stability and security of the Middle East”.

Prince Mohammad Bin Nawaf, the Saudi ambassador, denounced the agreement with Iran as a “dangerous gamble, about which we cannot remain silent”.

The US official acknowledged that Saudi Arabia was “completely unhappy — to put it mildly — that they weren’t in the loop”.

But the fact that America and Iran were talking was “closely held” information even within the US administration. “There was a fundamental decision made that that was the best way to do it,” said the official. This was the surest way of achieving the “fundamental goal” of settling the confrontation over Iran’s nuclear ambitions.

Since the agreement, the US has told Saudi Arabia that the “outcome is in your interests”, the diplomat added. The deal reduced the risk of another war in the Middle East, which was the “last thing” Saudi Arabia would have wanted.