According to official reports, Bernie Kerik, a former New York Police Commissioner who was nominated to head the Department of Homeland Security, Monday began a prison term for tax fraud.

ABC News has reported that Kerik, 54, who gained national stature for his performance as police commissioner after the Sept. 11, 2001, terrorist attacks on the World Trade Center, is serving a four-year sentence at a federal minimum-security prison in Cumberland, Md.

Kerik had nothing to say to reporters as he departed from his New Jersey home, the network reported.

Kerik posted a statement on his company's Web site expressing his disappointment with prosecutors and the courts regarding his sentence, the New York Daily News has reported.

He said, "I have repeatedly expressed remorse for what I may have done, however, unlike many, I can't remain silent in the face of what I believe has been a gross injustice, which I pray will be remedied."

The report further said that prosecutors has said that Kerik, while New York City corrections commissioner, let a construction company pay for renovations to his apartment in New York. The company had an interest in gaining his help in obtaining a city license. (With inputs from Agencies)