NEW YORK: The Boeing Co. on Thursday offered new details on its proposed passenger aircraft deal with Iran and rejected suggestions that it had not done sufficient homework in identifying end users of the planes.

In a letter to congressional critics of the politically delicate deal, Boeing said Iran Air, the national airline, intended to buy 80 passenger planes in a variety of models worth $17.6 billion and lease 29 of the company’s 737s, with deliveries projected to begin as early as next year.

The letter, by Tim Keating, vice president of government operations, also said “we have a vigorous compliance mechanism at Boeing with regard to the screening of all parties with which we do business.”

Keating wrote that Boeing had strictly adhered to dealings with Iranian entities approved by US sanctions monitors.

“We could not, as a corporation, be reasonably expected to have better intelligence resources than that of the US government,” Keating wrote. “Therefore, we do rely upon the US government to provide the information needed for us to remain compliant.”

Boeing’s proposed deal with Iran Air, disclosed this month, is potentially one of the most significant economic outcomes of the international nuclear agreement with Iran that took effect in January, which rescinded or eased many sanctions in exchange for Iran’s verifiable commitments to peaceful nuclear activities.

Among the eased sanctions was a relaxed prohibition on Iran’s ability to acquire aircraft for the national airline’s ageing commercial fleet.

Iran also has negotiated an agreement with Airbus, Boeing’s major competitor, to acquire more than 100 aircraft.

The sale and lease of Boeing jetliners, if completed, would constitute the biggest American business transaction with Iran since the 1979 Islamic revolution.

Other non-nuclear sanctions imposed by the United States against Iran remain. They include a prohibition on the use of the dollar by Iran and its exclusion from the American banking system, complicating how Boeing would get paid. Boeing’s products also cannot be used by sanctioned entities in Iran, notably the Islamic Revolutionary Guards Corps.

Keating was responding to a June 16 letter from two Republican congressmen, Peter Roskam of Illinois and Jeb Hensarling of Texas, who have been highly critical of any steps toward more normalised dealings with Iran after more than four decades of mutual hostility and mistrust.

The congressmen, citing the United States’ designation of Iran as a state sponsor of terrorism, and what they described as Iran’s systematic use of its commercial aircraft to aid “hostile actors around the world,” requested that Boeing explain how the company would prevent Iranian use of Boeing planes for such purposes.

Their letter also pointed out that five years ago, Iran Air had been sanctioned by the United States for transporting military equipment on behalf of the Islamic Revolutionary Guards Corps and Iran’s Defence Ministry. While the sanctions designation against Iran Air was later dropped, the congressmen wrote, “there is no reason to believe the company has ceased its malicious activity.”

Keating said in the response that Boeing had negotiated legally with Iran under the conditions allowed by the nuclear agreement, known as the Joint Comprehensive Plan of Action.

He also wrote that Boeing had reached no decisions yet on how to handle the Iranian financing for the aircraft, and reiterated the company’s previous pledges to follow the US government’s determinations of what is allowed.