Michal Konrad Herba, 36, appeared in court for an extradition hearing following his arrest in Tividale, West Midlands, on Wednesday.
He is the brother of Lukasz Pawel Herba who is being held by Italian police over the alleged kidnap in Milan.
Michal Herba denies involvement. The case was adjourned until 25 September.
Prosecutor Florence Iveson told the court that he was suspected of kidnapping and unlawfully detaining Ms Ayling in a "joint enterprise" with his brother and other "unidentified persons".
The 20-year-old model was allegedly drugged and a ransom of â‚¬300,000 (Â£270,000) was demanded, the court heard.
Defence lawyer Katherine Newbey said "no evidence had been served in the case" and her client "denies involvement".
Mr Herba did not consent to extradition, meaning that a full hearing will have to take place.
Deputy Senior District Judge Tan Ikram remanded the suspect in custody, saying he was satisfied there were "substantial grounds" to believe he would fail to surrender if he was released.
Mr Herba is due to appear in the same court by video link for a bail application on 23 August.
A full extradition hearing has been scheduled for 25 September.
Ms Ayling, from Coulsdon, south London, arrived in Milan on 10 July for a photo shoot.
Italian police say she was attacked by two men, drugged with ketamine and abducted, apparently to be sold in an online auction.
She is believed to have been transported in a bag to an isolated village near Turin, Italy, but was released on 17 July.
Ms Ayling's lawyer Francesco Pesce has said she was told she would be sold in the Middle East "for sex".
Speaking after the alleged abduction, Ms Ayling said she feared for her life throughout the "terrifying experience".
"I'm incredibly grateful to the Italian and UK authorities for all they have done to secure my safe release," she said.
Italian police documents claim that suspect Lukasz Herba said he had got involved in order to raise money for cancer treatment.
The Polish national, who lives in Oldbury in the West Midlands, told investigators he drove her to the British consulate in Milan and released her before the sale went ahead.

Kingsley Burrell, 29, died from cardiac arrest after being arrested following a disturbance in Birmingham in 2011.
An inquest in 2015 found restraint had been a factor in his death. The officers have also been charged with perverting the course of justice.
Constables Paul Adey, 36, Mark Fannon, 45, and Paul Greenfield, 50, have been suspended by West Midlands Police.
The charges relate to evidence given during Mr Burrell's inquest, the force said.
More updates on this story and others in Birmingham
"After investigation by the IPCC, the matter was referred to the Director of Public Prosecutions who has authorised the charges," it said in a statement.
The officers, who are all based at the Birmingham West and Central police station, will appear at the city's magistrates court on 31 October.
Mr Burrell was arrested and sectioned after calling police claiming two men has put a gun to his head. Days later he died from after a cardiac arrest at Queen Elizabeth Hospital in Birmingham.
An initial investigation by the CPS found in July 2014 there was insufficient evidence to prosecute anyone over Mr Burrell's death.
But an inquest a year later concluded prolonged restraint and a failure to provide medical help had contributed to his death.
The CPS relaunched a second investigation after the IPCC found there was a case to answer for gross misconduct against three officers, on the grounds of honesty and integrity.
Mr Burrell's family, who have held several protests demanding answers over his death, said the decision had been "a long time coming".
"The Burrell family welcome today's decision to prosecute the three officers concerned, in the belief that they must be publicly held to account for their actions in the circumstances surrounding the death of Kingsley," it said in a statement.
"This has been a long time coming and the fight for Justice for Kingsley continues."
The brother of the alleged captor of British model Chloe Ayling is to fight extradition to Italy, Westminster Magistrates' Court has heard.
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Three police officers have been charged with perjury following the death of a student in custody five years ago.