The Federal Government said Abaribe was aware that Kanu "has long violated the bail conditions handed down by this honourable court".
The Federal Government had accused Abaribe of harbouring Kanu, who 'disappeared' after the military allegedly raided his Abia home.
In FG's counter-affidavit against Abaribe's application seeking to withdraw as one of the sureties for Kanu, the government said Kanu should produce him for the continuation of his trial.
The Federal Government filed the counter-affidavit before the Federal High Court in Abuja.
Responding to the FG's accusation that Kanu is in his custody, Abaribe said he does not know the IPOB leader's whereabouts.
"I don’t know where he is," the senator wrote in a text message sent to Punch.
The Federal Government, however, insists that Abaribe was aware that Kanu "has long violated the bail conditions handed down by this honourable court" before September 11 when he claimed to have lost contact with the defendant.
The counter-affidavit read in part, "That it was at this point at violating the conditions at the bail that the senator surety ought to surrender the 1st defendant and or bring up this application; That this application is belated and ill-timed.
"The applicant failed to apply to the court timeously, stating on oath that the defendant bound by recognizance to appear before this court had violated the bail condition given by this court."
Kanu was absent from court when his case came up on October 17, 2017, but his co-defendants with whom he was being prosecuted on charges of treasonable felony were produced in court by prison officials.