Neil Davidson, 28,  of no fixed address, was remanded in custody after he appeared in court on Monday.
He is charged with importing and possessing cocaine and heroin with intent to supply.
Mr Davidson was arrested in a car at West Bank Road in the city's docks area on Friday evening.
The court in Belfast heard that cocaine worth £960,000, heroin worth £500,000 and cannabis worth £2,000 was seized.
A detective said he believed Mr Davidson was a member of an organised crime gang based in Dublin with connections to Northern Ireland and Holland.
Opposing bail, he said he was concerned that Mr Davidson would abscond, commit further offences or that there could be a threat to his personal well being.
The detective said he believed Mr Davidson did not act alone, however, he refused to identify others involved.
A defence lawyer told the court that Mr Davidson had serious health problems. He does not have a criminal record.
Bail was refused and he was remanded in custody until 24 October.
Police believe a man arrested over a £1.5m drugs haul belongs to a Dublin crime gang with links to Northern Ireland and Holland, a court has heard.