The San Francisco 49ers have placed linebacker Aldon Smith on their reserve/non-football injury list as he deals with personal problems.

Smith was arrested last week in San Jose under suspicion of driving under the influence of alcohol, but played in Jim Harbaugh's side's defeat to the Indianapolis Colts on Sunday.

However, after the game team chief executive officer Jed York confirmed that the 23-year-old would be leaving the side temporarily to seek treatment for his problems.

"I am taking a leave of absence to address my health," Smith said in a statement on the club's official website. "I am sorry that I have affected my team, my family and the organisation. I will do everything in my power to handle this situation the best way possible. I appreciate the support of the 49ers and our fans."

"Aldon Smith is taking a leave of absence to address a personal matter," general manager Trent Baalke added. "The 49ers organisation both respects and supports Aldon's decision and commends him for taking responsibility for his actions.

"The long-term well-being of our players is paramount and we will stand by Aldon as he works toward addressing this issue. Due to the private nature of the matter, we will have no further comment."

The 49ers face the St Louis Rams on Thursday.