US citizen Laura Wang-Woodford, a director of a lucrative Singapore-based import-export business, was arrested in December as she entered the United States, according to a letter submitted by US attorneys to the presiding US District Court judge.

Monarch Aviation Pte Ltd exported military aircraft parts from US suppliers to Singapore without proper licenses, falsely identifying them as civilian components, the letter alleged.

It also illegally resold commercial aircraft parts to a company in Tehran, in violation of the International Emergency Powers Act, a US law barring transactions to protect against national security threats.

At the time of her arrest Ms Wang-Woodford was carrying two merchandise catalogs from a Chinese company listed as a proliferator of weapons of mass destruction by the US Treasury Department, the letter alleged.

Ms Wang-Woodford was arrested at San Francisco International Airport on Dec 23, 2007, as she attempted to enter the United States for the first time in many years.

She had departed Singapore on Dec 18 and spent five days in China before travelling to the United States, according to the letter.

Ms Wang-Woodford runs Monarch Aviation together with her British-born husband Brian Woodford who is still at large.

A New York grand jury returned a 20-count indictment against the two in January 2003 that was under seal until late 2007, according to ABC news, which broke the story on Thursday.

'The offences charged in the indictment are serious in nature, involving conduct that could impact the national security of the United States,' the letter stated, urging the judge to keep Wang-Woodford behind bars. -- AFP