Another courier-delivered parcel, sent from Latin America and addressed to the same suspect in the city, was then redirected to London, prosecutors said on Monday.
Metropolitan police officers and the Serious Organised Crime Agency have now joined in the PSNI operation against the international organised crime group allegedly involved.
Details were revealed as bail was refused to one of three men charged in connection with the original haul from Mexico.
Philip Devlin, 28, of Antrim Road, Belfast, faces charges of conspiracy to supply cocaine, importing and possessing Class A drugs.
He was detained last month along with co-accused Christopher Overend, 22, of Hillman Street, Belfast and Nigerian national Abiodun Dahunsi, 35, of Mount Alverno, Ballymurphy.
The first consignment of high-purity drugs was said to have been hidden in boxes of rechargeable batteries.
They were addressed to Devlin and delivered by courier service to an apartment at Sans Souci Park in the city on 8 May, the court heard.
According to the prosecution Overend collected the parcel before both men were arrested in the lower Ormeau area.
Three kilos of 82% pure cocaine was discovered, with an estimated value of £2m.
A judge was told the drugs sold on the street would normally have a 3-5% purity level.
Devlin has only been charged in connection with that seizure. But it was disclosed that another parcel in the same name was originally sent to Sans Souci Park around a week later.
Tessa Kitson, prosecuting, said it was redirected to London and found to contain more major quantities of cocaine, this time 76% pure.
"Police advise that the street value of the second package rerouted to London was some £4m," she told the court.
The barrister added: "That was intercepted and people have been arrested as a result of that."
"This has involved the Metropolitan Police, the Serious Organised Crime Agency and the PSNI."
Opposing Devlin's application for bail, she said he was alleged to be "intrinsically linked to members of an organised criminal group which operates internationally".
Defence counsel Jon Paul Shields challenged the prosecution assessment, arguing that his client had been used as a "patsy" in the drug smuggling operation.
The court was told Devlin allegedly agreed to pick up the parcel in return for a £1,000 payment.
He was said to have fully cooperated with the police investigation, giving them the names of others involved.
Mr Shields added: "He also indicated that he was put under pressure and threatened to the extent that duress may become a live issue, and that a gun was produced."
But Mr Justice Mclaughlin held that the risk of re-offending could be greater if Devlin was being pressured by others.
Refusing bail, the judge said: "Given the sheer scale, not just economically and financially, but globally, of this operation, it is quite clear this is not a case for bail."