Reuters- President Barack Obama's administration said on Monday he would veto legislation seeking to block financial transactions related to the export of passenger aircraft to Iran, saying it would undermine the nuclear deal implemented early this year.

The legislation in the House of Representatives is the latest Republican-led effort to stop the sale of aircraft to Iran by Airbus and Boeing Co, allowed under the nuclear deal.

The White House said U.S. partners would view the bill, if implemented, as a violation of the nuclear agreement. The United States plus Britain, Russia, France, China and Germany agreed to lift sanctions if Iran would curtail its nuclear program.

The deals by Airbus and Boeing to sell or lease over 200 jets to IranAir would help modernize and expand the country's elderly fleet, held together by smuggled or improvised parts after years of sanctions.

Some members of Congress have raised concerns that killing the sale could cost jobs. But opponents argue that the passenger aircraft could be used for military purposes such as transporting fighters to battle U.S. troops or allies in Syria.

The measure would bar the Secretary of the Treasury from authorizing a transaction by a U.S. financial institution related to the export, or re-export, of commercial aircraft to Iran. And it would revoke any authorities enacted before the bill passed, such as those that allowed the Boeing and Airbus sales.

The measure also limits the role of Export-Import Bank financing of sales to Iran.

Some banks have been reluctant to finance the aircraft deals, fearing they could fall foul of remaining sanctions prohibiting the use of the U.S. financial system for Iranian business.

The House is expected to take up, and pass, the measure as soon as this week.

It is not expected to get through the Senate, where it would need Democratic support to advance.

Lawmakers expect more efforts to stop the aircraft sale, and the broader Iran deal, after Donald Trump becomes U.S. president in January.

Trump has been critical of the nuclear agreement, which is seen by Obama supporters as one of the Democratic president's signature foreign policy achievements.

(Reporting by Patricia Zengerle; Editing by Lisa Shumaker)