Former UFC middleweight champion Israel Adesanya was allegedly detained for bringing brass knuckles past security at New York's John F. Kennedy Airport.

The 33-year-old was detained by Port Authority police at the American Airlines terminal on Wednesday after losing his championship by TKO to Alex Pereira in New York last Saturday.

According to the Daily Mail, a Port Authority representative at New York's John F. Kennedy Airport confirmed the incident, stating Adesanya was arrested for possessing 'metal knuckles.'

Brass knuckles are a Class A misdemeanor in New York, and they are also prohibited on airplanes. It is unclear where Adesanya reportedly kept the firearm.

The UFC has yet to issue a statement in response to the incident.

Adesanya's defeat has pushed him down the pound-for-pound rankings, from No. 2 to No. 8 on MMAfighting.com.

Adesanya, a native of Lagos, Nigeria, is now a New Zealand citizen and resides in Auckland.

Longtime rivals Adesanya and Pereira squared off on Saturday for the UFC middleweight title, with the latter emerging triumphant following a stunning TKO finish late in the fight.

Despite concerns that referee Marc Goddard prematurely ended the bout, Canadian boxer and trainer Firas Zahabi believes Adesanya should be 'grateful' for the decision.