U.S. President-elect Donald Trump has often boasted about the strict confidentiality pledges he exacts from his employees.

Now a legal challenge to one of those agreements is pending before a U.S. agency over which he will soon have influence, potentially posing an early test of concerns about conflicts of interest between Trump's public role and his business empire.

In September, a worker-advocacy group filed a charge with the National Labor Relations Board claiming a nondisclosure contract used by Trump is unlawfully broad. The contract prohibits employees, independent contractors and even volunteers from ever disclosing any information that Trump deems confidential about his personal, business or political life.