DETROIT — A monitor appointed by a federal judge in the wake of a United Auto Workers bribery and embezzlement scandal contends that the union has been uncooperative by withholding information on additional misconduct allegations.

The monitor, Neil Barofsky, made the assertion in his third report to Judge David Lawson in Detroit. Barofsky accused the union of concealing an investigation into the mishandling of cash by an assistant regional director of the UAW.

Barofsky alerted the U.S. Attorney’s Office in Detroit, which investigated the original scandal. U.S. Attorney Dawn Ison told the union that it was violating a court order by concealing the information, and the UAW has been behaving properly since, Barofsky wrote.

But he wrote that the union was obstructing him.

“The union’s concealment of evidence of the misconduct of one of its leaders and its own investigation into that misconduct interfered with the monitor’s ability to carry out his work,” Barofsky wrote.

His assertions raise questions about whether the union has reformed itself as it has announced, and whether Ison’s office has begun further investigations.

A spokeswoman for Ison declined to comment.

In a statement, the union said it’s committed to rebuilding trust and transforming the UAW’s culture.

“We have proven that with a myriad of already implemented changes to policies and the creation of processes that ensure accountability,” the statement said.

The union, the statement said, would balance the need to make reforms with the mandate of bargaining for equitable contracts.