Enrique Marquez
Enrique Marquez (C), 24, is shown in this courtroom sketch as he appears with legal representatives during a hearing in federal court in Riverside, California, December 17, 2015REUTERS/Bill Robles

Enrique Marquez, the man accused of providing Syed Farook and Tashfeen Malik the assault-style rifles they used to kill 14 people in San Bernadino has been denied bail, a US magistrate judge ruled on 21 December.

During Marquez's second court appearance, prosecutors argued that the 24-year-old was a "serious" flight risk if released.

While US District Magistrate Judge David Bristow sided with Marquez's defence team that he was not a flight risk, Marquez's alleged plot with Farook was justification enough to keep him detained, The Los Angeles Times reported.

Judge Bristow said the alleged conspiring with Farook is more critical than the fact that he has lived with his parents and does not own a passport.

"But the grave harm that is presented to the community by that conduct was demonstrated on Dec 2," the judge said. "The gravity of such conduct...is such that at this point in time the defendant has not rebutted the argument that he is a danger to the community and he continues to post that danger."

Marquez was charged with conspiring with Farook to commit crimes of terrorism in 2011 and 2012, unlawfully purchasing two assault rifles that were used in the San Bernardino attack and for defrauding immigration officials by entering a fraudulent marriage with Farook's in-law.

According to the Los Angeles Times, officials say they do not have evidence that Marquez collaborated with the married couple in the deadly massacre at Inland Regional Center.

Farook and Malik killed 14 people and injured 22 on 2 December before being killed during a police shoot out. Marquez called 911 shortly after the shooting, threatening to kill himself and admitting that Farook had used guns he owned.

Marquez, who is being held without bail, will appear for another court hearing on 4 January 2016. He has yet to enter a plea.