WASHINGTON  Months before the BP disaster, some Congressional officials were pressing federal regulators behind the scenes about numerous safety concerns related to offshore drilling, potential oil spills and BP itself, but they complained that they were rebuffed, previously undisclosed documents show.

Congressional officials raised particular concerns about the safety of a second BP oil platform in the Gulf of Mexico and about regulators’ failure to spend millions of dollars approved for oil spill research, among other issues, according to e-mails between Congressional officials and regulators at the Minerals Management Service, as the agency was then known.

When officials at the agency told members of Congress in 2009 that they could not specifically respond to concerns about the potential for a “catastrophic” accident on a second BP rig off New Orleans, known as the Atlantis, some staff members were livid at what they viewed as stonewalling.

“Just so I have this straight,” an aide to Representative Sander M. Levin, a Michigan Democrat, wrote in an e-mail to a mineral agency official, “I am to tell my boss that M.M.S. has nothing to say about this Atlantis business” beyond the general comments it had already made?