Niners linebacker Aldon Smith was arrested Sunday at Los Angeles International Airport after claiming he had a bomb during a security screening, airport police said.

Smith, 24, made the threat after he was randomly selected for a second screening at about 2 p.m. as he went through the Transportation Security Agency checkpoint for Terminal 1.

“The suspect then became belligerent and uncooperative with the process and with the TSA agent, making a comment indicating that he was in possession of a bomb before proceeding toward the gate area,” Sgt. Karla Ortiz said in a statement.

Smith was transported to the Los Angeles Police Department’s Pacific Community Police Station where he was booked for felony false report of a bomb threat, which is punishable by up to a year in jail. He was released at 7:02 p.m. on $20,000 bail.

Smith’s arrest was the latest in a string of arrests including the most recent on Sept. 20 on a charge of driving under the influence. He was arrested on the same charge in January 2012. Smith also faces three felony weapons charges stemming from a party at his house in June 2012, during which he reportedly fired a gun into the air and was stabbed while two others were shot. He pleaded not guilty to the weapons charges.

Sgt. Ortiz said witnesses present when Smith was detained said he “appeared” to have been drinking, but alcohol “was not relevant or a factor for his arrest and booking.”

“We are disappointed to learn of the incident today involving Aldon Smith,” 49ers general manager Trent Baalke said. “As this is a pending legal matter and we are still gathering the pertinent facts, we will have no further comment.”

In November, following a five-week stint in an inpatient rehabilitation facility for a substance abuse problem, Smith vowed to make sure he stayed out of trouble off the field.

“I’m getting there,” Smith said at the time. “Every day is just a step closer to getting where I want to be.”

The 49ers have until May 3 to exercise the fifth-year option on Smith’s rookie contract, which is set to expire after the 2014 season. If they do exercise the option, Smith would earn $9.75 million in 2015.

Based on his on-field performance, Smith, a first-team All-Pro selection in 2012, is worth the fifth-year investment: Despite coming off the bench in 2011 and missing five games for his rehab stint, his 42 sacks after his first three seasons rank third behind Hall of Famers Reggie White (52) and Derrick Thomas (43.5). Sacks became an official NFL statistic in 1982.

Today’s incident added to a string of Niners offseason player woes.