WASHINGTON (Reuters) - The attorneys general of Maryland and the District of Columbia on Tuesday formally demanded financial records from U.S. President Donald Trump’s businesses as part of their lawsuit alleging his dealings with foreign governments violate anti-corruption clauses of the U.S. Constitution.

District of Columbia Attorney General Karl Racine (L) and Maryland Attorney General Brian Frosh conduct a live television interview after their news conference to announce their lawsuit against U.S. President Donald Trump on the issue of the U.S. Constitution's emoluments clauses and Trump's business ventures, in Washington, DC, U.S. June 12, 2017. REUTERS/Jonathan Ernst

The attorneys general issued subpoenas to the Trump Organization Inc, the president’s privately owned real estate company, and related corporate entities.

The flurry of subpoenas came one day after U.S. District Judge Peter Messitte in Greenbelt, Maryland, began the case’s discovery phase, which allows litigants to demand answers to specific questions and production of sensitive documents.

The U.S. Department of Justice, which is defending the president in the litigation, did not immediately respond to a request for comment.

Among other documents, the attorneys general are seeking revenue statements and tax returns from the Trump Organization entities.

Ignoring the subpoenas would result in a finding of contempt of court, said George Brown, a professor at Boston College Law School.

The development “brings us closer to judicially enforced discovery about the Trump empire,” said Brown. “It will probably tell us a lot we don’t know because nobody is going to hide that stuff in the face of a subpoena.”

U.S. government lawyers said on Friday in a court filing that they plan to ask an appeals court to halt discovery and review earlier rulings by Messitte that allowed the case to proceed.

Such requests for an expedited appeal rarely succeed, Brown said, but in this case the odds are higher because the case raises novel legal questions that the appeals court may want to address quickly.

The lawsuit, filed in June 2017, alleged the Republican president failed to disentangle himself from his hotels and other businesses, making him vulnerable to inducements by officials seeking to curry favor.

The lawsuit accused Trump of violating the Constitution’s “emoluments” provisions designed to prevent corruption and foreign influence. One bars U.S. officials from accepting gifts or other emoluments from foreign governments without congressional approval. The other forbids the president from receiving emoluments from individual states.

Messitte later narrowed the case to claims involving the Trump International Hotel in Washington and not Trump’s businesses outside of the U.S. capital.