Chicago police believe Empire actor Jussie Smollett may have paid two men to carry out last month's alleged assault, reports in the US say.

Two Nigerian brothers who had worked as extras on Empire told police that they were paid to take part in the 29 January attack, police sources said.

Smollett had said he was attacked by two white men.

His lawyers have strongly denied he played any role in the alleged homophobic and racist assault.

"Nothing is further from the truth and anyone claiming otherwise is lying," they said in a statement.

The statement said one of the brothers had worked as Smollett's personal trainer.

Ola and Abel Osundairo have both appeared as extras on Empire. In this Instagram post, Ola Osundairo (R) is seen alongside Empire creator Lee Daniels (C).

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#Repost @theoriginalbigdaddy ・・・ Ummmm ... #prisonlife? 💋 #freelucious #empireseason2 #day1 #bigdaddylostintheyard 👀

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What's the latest?

The Nigerians, aged 25 and 27, left the US after the alleged 29 January attack. They were arrested on their return on Wednesday but were released on Friday and are now reported to be working with police.

On Saturday Chicago police said the investigation of their attack had "shifted", having previously dismissed earlier suggestions that the attack had been staged.

Chicago police released this CCTV image of two "people of interest" in the case

The Nigerians said they had bought the rope used in the attack at a nearby hardware store, police sources told US media.

Police searching their flat found ropes, masks and bleach, CBS reported.

What has Smollett said?

Smollett said the alleged attackers hurled racial and homophobic insults as they punched him, poured a chemical substance over him, and put a rope around his neck.

"This is Maga country," he says they told him, referring to President Donald Trump's Make America Great Again slogan.

The actor said he had been "forever changed" by the incident.