San Francisco 49ers linebacker Aldon Smith has been suspended for nine games by the NFL for violating its policy on personal conduct and substances of abuse.

The 24-year-old had a trouble-laden off-season as he received a 12-day sentence and a three-year probation period for three felony weapons charges and also two DUI charges.

Smith will now miss all of his side's games up to week 11 of the season, but will be allowed to be around the team's facility during the suspension.

49ers general manager Trent Baalke said in a statement: "Our organisation has known this decision would come and we have prepared for it as a team.

"Aldon has taken responsibility for his actions and has continued to show growth personally and professionally.

"We will continue to support him, but it is time to put this matter behind us and focus on the season ahead."

The linebacker also missed five games in the 2013 campaign after voluntarily taking a break from the sport to seek professional help following a DUI charge.