Hewlett-Packard Co. said it’s conducting an “intense” internal investigation and has uncovered extensive evidence of improper accounting at Autonomy Corp., a software company it bought last year.

Responding to a letter by former Autonomy Chief Executive Officer Mike Lynch calling on Hewlett-Packard’s board to explain its allegations, Hewlett-Packard said that the matter was now in the “hands of authorities.”

“While Dr. Lynch is eager for a debate, we believe the legal process is the correct method in which to bring out the facts and take action on behalf of our shareholders,” Hewlett-Packard said in an e-mailed statement.