Chicago police have released two Nigerian brothers who had been arrested earlier in the week on suspicion of assaulting Empire actor Jussie Smollett.

The men were picked up by police on Wednesday at Chicago’s O’Hare International Airport as they returned from Africa and their apartment was searched the following day.

They were questioned on Friday but police were obliged to release them as they had not been charged within 48 hours.

Police spokesman Anthony Guglielmi tweeted: “Due to new evidence as a result of today’s interrogations, the individuals questioned by police in the Empire case have now been released without charges.”

Chicago police said they have new evidence to investigate as a result of questioning the men, but did not elaborate further.

Smollett says he was assaulted on January 29 by two men who shouted racial slurs and put a rope around his neck, including a reference to president Donald Trump’s campaign slogan “Make America Great Again”.

Smollett, 36, said he was out getting food at a Subway sandwich shop in Chicago when the attack happened.

Police earlier this week said there was “no evidence to say that this is a hoax” and that Smollett “continues to be treated by police as a victim, not a suspect”.

Police have said they found no surveillance video of an attack but are continuing their investigation.

He said police also are contacting stores in the hope of finding out who bought the rope that was around Smollett’s neck.

In an interview with ABC News, the singer and actor said he did not remove the rope from around his neck before police arrived “because I wanted them to see.”

Smollett also said he initially refused to give police his mobile phone because the device contained private content and phone numbers.

He later gave detectives heavily redacted phone records that police have said are insufficient for an investigation.