Macau's Banco Delta Asia filed a petition in Washington against the US Treasury Department, alleging its blacklisting of Banco Delta from the US financial system over the bank's links to North Korea was politically motivated. In an opening legal shot at the department, the 31-page petition describes the department's actions as "arbitrary and capricious," the South China Morning Post reported. Senior diplomatic sources said the move would further complicate the troubled drive to rid North Korea of its nuclear weapons. The Treasury Department's decision last month to blacklist Banco Delta under the US Patriot Act takes effect on Wednesday. Denying the private, family-owned bank any access to the US financial system would effectively strangle any further international access, according to analysts. The blacklist follows the department's announcement in September 2005 that Banco Delta had served as a "willing pawn" during 30 years of state-sponsored crime by North Korea that included drug trafficking and counterfeiting. That announcement sparked a run on the bank, government intervention and the freezing of US$25 million across 50 accounts linked to North Korea.