Federal investigators are exploring whether BP PLC representatives lied to Congress about how much oil was leaking after the Deepwater Horizon accident two years ago, a development that could lead to additional criminal charges against current and former company employees.

Prosecutors are examining statements made by BP officials to members of Congress, including those from a May 4, 2010, briefing where they discussed the best guesses for the rate at which oil was spilling from the damaged well following the April 20 accident, according to people familiar with the investigation.