U.S. Commerce Secretary John Bryson has resigned after being involved in a traffic accident when he suffered a seizure earlier this month, and U.S. President Barack Obama praised him as an effective leader.

Bryson said he decided to leave office after leading the Commerce Department for less than a year "as a consequence of a recent seizure and a medical leave of absence", noted his letter presented to Obama on Wednesday.

Bryson, the 68-year-old former utility company executive, said that the seizure he suffered on June 9 could be a "distraction" from his duty as Commerce Secretary, as this was a "critical period" for the U.S. economy.

"Last night I accepted the resignation of John Bryson as Secretary of the Department of Commerce. I want to extend my deepest thanks and appreciation to John for his service over the past months, and wish him and his family the very best," Obama on Thursday said in a statement.

"As Secretary, John fought tirelessly for our nation's businesses and workers, helping to bolster our exports and promote American manufacturing and products at home and abroad," Obama said.

"John has proven himself an effective and distinguished leader throughout his career in both the public and private sectors, from his success in the business world to his work leading on issues in the renewable energy industry," Obama added.

Bryson was being investigated for his role in two car crashes including a hit-and-run accident, near his Los Angeles-area home on June 9.

"I am grateful that he brought that invaluable experience and expertise to my administration, and am pleased that he has agreed to continue supporting our efforts to strengthen the economy and create good jobs by serving as a member of my Export Council going forward," Obama noted.

The Export Council, an advisory committee on international trade, is composed of leading U.S. corporate executives and high- ranking officials aiming at promoting U.S. exports.

Bryson on June 11 transferred his functions and duties as Commerce Secretary to Deputy Secretary Rebecca Blank, as he decided to take a medical leave of absence two days after the traffic accident.

"The work that you do to help America's entrepreneurs and businesses build our economy and create jobs is more important now than ever and I have come to the conclusion that I need to step down to prevent distractions from this critical mission," Bryson said on Thursday in a separate letter to employees of the Commerce Department.

"I am confident that Dr. Rebecca Blank will serve the American people well as Acting Secretary and that the Commerce Department staff will continue their tireless work putting forward policies that help our workers and businesses compete," Obama added.

According to local police, Bryson was allegedly traveling southbound in a Lexus on San Gabriel Boulevard in the City of San Gabriel, California on June 9, and rear-ended a Buick occupied by three males.

Bryson drove into the neighboring city of Rosemead, and allegedly caused a collision involving a second car. He was found alone and unconscious behind the wheel of his vehicle.

Officials of the Commerce Department said that he had not suffered a seizure previously.

Obama met with Bryson on Thursday afternoon at the White House. Bryson has served as Obama's Commerce Secretary since October 2011.

Obama met with Bryson to thank him for his service both in the public and private sectors, White House spokesman Jay Carney told reporters on Thursday.