US Vice President Joe Biden (R) points to some faces in the crowd with his son Hunter as they walk down Pennsylvania Avenue following the inauguration ceremony of President Barack Obama in Washington, in this January 20, 2009 file photo. [Photo/Agencies]

WASHINGTON - The son of Vice President Joe Biden was discharged from the US Navy reserve earlier this year after testing positive for cocaine, sources familiar with the matter said on Thursday.

The sources, who were not authorized to speak on the record, said Hunter Biden tested positive for cocaine in a drug test administered in June 2013.

Navy spokesman Commander Ryan Perry confirmed that Biden was discharged from the Navy reserve in February 2014 but said privacy laws prevented him from releasing any details.

Perry said Biden was selected for a direct commission in the Navy Reserve as a part-time ensign in 2012 and was assigned to a public affairs unit in Norfolk, Virginia in May 2013.

Biden, 44, a partner at an investment firm, said he regretted the incident.

"It was the honor of my life to serve in the US Navy, and I deeply regret and am embarrassed that my actions led to my administrative discharge," Biden said in a statement provided by his lawyer. "I respect the Navy's decision. With the love and support of my family, I'm moving forward."

The vice president's office referred all queries to Hunter Biden's attorney.

The vice president's other son, Delaware Attorney General Beau Biden, served a year-long tour in Iraq as a captain in the Delaware Army National Guard.