Cocaine seizures at the port of Antwerp, the main gateway for illegal drugs into Europe, hit a new record last year, as Belgian and Dutch authorities face off against violent international gangs.

The annual figures for drug busts in Belgium and the Netherlands were released on Tuesday, a day after an 11-year-old girl was shot dead in an attack on an Antwerp home that the city's mayor alleged was part of an ongoing "drug war".

Belgium's main container terminal is now seen as the biggest route for illegal drugs into Europe, with 109.9 tonnes seized in 2022 – up from 89.5 tonnes the year before – and an unknown but probably much larger quantity reaching the market.

Across the Netherlands border, in nearby Rotterdam and Vlissingen, Dutch police battling the same gangs intercepted a further 52.5 tonnes. After Belgium and Spain, the Netherlands is Europe's third largest drugs gateway.

Belgium's Finance Minister Vincent Van Peteghem, who oversees the customs service, and Dutch secretary of state Aukje de Vries, revealed the figures at an Antwerp news conference.

They hailed the "intense cooperation" between the neighbouring authorities and promised to hire 100 more Belgian customs officers while investing 70 million euros (US$75 million) in high-tech tools.

"For the Netherlands, the next few years' spending will relate in particular to artificial intelligence, chemical detection and tracking containers," a joint statement said.

European police have made a number of high-profile arrests after cracking an encrypted text message network used by the gangs, and several large-scale drug busts in recent weeks.

But the cocaine volumes found in Antwerp have only increased and there have been explosions and gun shots in city neighbourhoods as rival groups settle scores.

On Monday, an 11-year-old girl was killed after attackers opened fire on a home. "A drug war is under way," Antwerp mayor Bart de Wever told local TV.

Antwerp prosecutors said five shots were fired through the garage door of a terraced house, fatally wounding the child. Cartridge casings found at the scene indicated a military-style weapon was used.

"The three other residents who were present at the time of the facts, a 58-year-old father and two other daughters aged 13 and 18, were taken to hospital with minor injuries," the prosecutor's office said.

"An investigation was launched for murder and attempted murder."

Prosecutors say over the past five years they have recorded more than 200 incidents of drug-related violence – mainly assaults and explosives thrown at homes.

The gangs, including the so-called "Mocro Maffia" that emerged from Moroccan-origin communities in the Netherlands, have become more brazen in recent years.

In September last year, security was stepped up around Belgium's Justice Minister Vincent Van Quickenborne after four Dutch suspects were arrested for allegedly plotting to kidnap him.

Sniffer dogs and police frogmen have been deployed at the Antwerp and Rotterdam container terminals, but authorities fear they are only intercepting 10 percent of illegal cargoes.

At a separate announcement in the Netherlands, Dutch authorities revealed that drugs seized at their ports in 2022 had a street value of 3.5 billion euros.

"In the port of Rotterdam we seized nearly 50 tonnes of cocaine which is lower than the year before when we seized 70 tonnes," Jan Kamp, Rotterdam's chief of customs, told reporters.

"But we look, together with the port of Antwerp, to the overall figure, and then you see combined we have seized the same amount of kilos as we did in '21, so it's all about 160 tonnes together."

"You see a shift, maybe, from Rotterdam to Antwerp. That could be one of the conclusions."

In Rotterdam seizures were down in 2022 to 46.8 tonnes compared to 72.8 the year before, but in smaller Vlissingen, just across the Scheldt river estuary from Antwerp, 4,157 kilos were intercepted in 2022, compared to 2,100 kilos in 2021.

According to city prosecutor Hugo Hillenaar, drug-related violence is rife in the Dutch port.

"In Rotterdam we have shootings on a daily basis – shooting at each other, shooting at houses, explosives on houses, intimidation," Hillenaar said.

Smugglers into the Netherlands appear to be breaking their shipments into smaller packages, perhaps to spread the risk of interception, but the biggest seizure was a 2.8-tonne batch in a load of frozen fish from Ecuador.

Cocaine is one of organised crime's biggest money earners. The European drugs monitoring agency estimated in 2020 that the EU retail cocaine market was worth between 7.7 billion and 10.5 billion euros. (AFP)