US lawmakers have approved legislation that prevents the sale of aircraft from the US’ Boeing and France’s Airbus to Iran.

The legislation undermines the recent memorandum of understanding (MoU) signed between Boeing and Iran Air, where the Islamic Republic’s flag carrier indicated an intent to purchase Boeing commercial planes.

The US House of Representatives approved two amendments to its Financial Services and General Government Appropriations Act. One amendment bans the Office of Foreign Assets Control (OFAC) from using funds to authorise a license necessary to allow aircraft sale to Iran. The second amendment prohibits US financial institutions from funding the purchase of militarily-fungible aircraft by denying the OFAC funds to authorise the financing of such transactions, US-based media reported.

The legislation, sponsored by Peter Roskam, a Republican, is said to have gained support even from Democrat lawmakers.

The US government gave Boeing clearance to begin commercial discussions with several Iranian airlines in April. However, this clearance has yet to allow Boeing to either start or complete commercial transactions with Iranian airlines.

The confirmation of the MoU by Boeing in June has been widely seen to pre-empt the granting of a license for Boeing to begin and complete a sale transaction to the Islamic Republic. Boeing has not supplied Iran with an aircraft since the 1979 Revolution.

Sources in Iran have said the MoU covered the supply of more than 100 passenger aircraft, including leasing of 29 aircraft, which could be valued at up to $25bn and with deliveries scheduled to start as early as 2017.

Boeing’s rival Airbus signed a deal to sell 118 passenger aircraft to the Islamic Republic in January, a transaction that is estimated to fetch $27bn based on list price.

The sale was understood to be partly funded by Italy’s Sace. The Islamic Republic’s frozen assets within the EU banking systems have been used as collateral for the loan.

The actual delivery of the Airbus aircraft to Iran, however, is still contingent upon US approval, since some Airbus components are manufactured in the US.

The Iranian government has said acquiring new planes is a priority following the lifting of nuclear-related international sanctions in January. It said it would require up to 90 new planes annually over the next five years to revive its antiquated fleet.