Colorado’s attempt to create a bank to service its marijuana industry has suffered another setback by the federal government and could be facing an impossible dilemma.

The Federal Reserve — the guardian of the U.S. banking system — said in a court filing Wednesday that it doesn’t intend to accept a penny connected to the sale of pot because the drug remains illegal under federal law.

The stance appears to mark a shift in the position of the federal government. Last year, the U.S. Treasury Department issued rules for how banks can accept pot money.

“We’re frustrated,” said Andrew Freedman, director of marijuana coordination for Colorado Gov. John Hickenlooper. “We tried to do the most with the building blocks of instructions they sent us, set up the most rigorous solution. And we still are left with confusion.”

The filing came in a legal battle between the Federal Reserve and the would-be Fourth Corner Credit Union, which was set up last year to serve Colorado’s $700 million-a-year marijuana industry. [Read more from the Associated Press at NBCNews.com]