Mrs Justice Keegan ruled there was a risk of flight and potential re-offending, saying: "I have therefore decided not to grant bail at this stage in the case."
She also said: "There may well be issues regarding the evidence to be debated in due course."
This appears to be a reference to claims that Dr Bassalat was entrapped by an undercover agent said to have been working for MI5.
Dr Bassalat has been on hunger strike in protest at being held in isolation at Maghaberry Prison, supposedly as a precaution against coronavirus. Around 50 Republican prisoners went on hunger strike in solidarity with him. Dr Bassalat was released from isolation on Tuesday, bringing an end to the hunger strike.
Chris Williamson of the Left Legal Fighting Fund said on Sunday:
"Dr Bassalat's hunger strike is an alarming symptom of something very wrong with the justice system in the north of Ireland, which appears to be beholden to the political goals of British intelligence services. Dr Bassalat should be immediately released from isolation."