BIZERTE - Dimming the lights on their patrol boat, Tunisian coastguards stand in silence scanning the sea for speedboats on clandestine missions to and from Italy.

Smuggling gangs are using high-performance vessels to ferry people, drugs and cigarettes across the Strait of Sicily, a distance of just 150 kilometres.

Commander Mohamed Naceur Saadani says their use of speedboats is a "new and dangerous" phenomenon.

Standing on the bridge of a patrol boat capable of 40 knots (about 70 kilometres per hour), he monitors a bank of glowing radar screens.

Patrolling Tunisia's northern coast during a 24-hour operation, the crew are on particularly high alert at night, as the smugglers prefer to operate under cover of darkness.

Migrants seeking a better future have long used Tunisia as a launchpad for bids to reach Europe.

But amid the turmoil that followed Tunisia's 2011 revolution that unseated strongman president Zine El Abidine Ben Ali, smugglers have strengthened links between the North African country and Italy, Saadani said.

While the northbound traffic consists mostly of clandestine migrants and cheap cigarettes, Tunisian authorities say they are dealing with a growing influx of drugs coming in the opposite direction.

In mid-March, Tunisia seized an "unprecedented" haul of more than 30 kilos of pure cocaine worth around $6.4 million (R85 million).

That shows that "a major international network is behind the operation", says Mohamed Walid Ben Ali, a coastguard at La Goulette port on the edge of Tunis.

National Guard spokesman Khalifa Chibani says Tunisia is mainly a transit point and the drugs are destined for neighbouring countries, particularly Libya.

'Faster boats than ours'

Saadani says traffickers had not previously been able to get drugs into Tunisia thanks to navy operations, but that if they succeeded once they would likely ramp up their operations.

He warns that the same smuggling routes could also be used for trafficking arms through Tunisian waters.

Chibani says the smugglers' high-performance speedboats pose an additional challenge for the coastguard.

"Tunisians living illegally in Italy organise these operations with Italian smugglers and use speedboats -- mostly stolen -- which are very advanced and faster than ours," Chibani says.

Smugglers who reach the Tunisian shore can load a boat with clandestine migrants and cheap cigarettes and set off again in as little as 15 minutes, he adds.

Chibani says that in late 2016 and early 2017, the coastguard spotted five speedboats from Italy, but they managed to escape.

The smugglers' high-tech equipment could be also used for "terrorist operations," he says.

"That represents a danger not just for Tunisia but also for Europe."

'Tunisia is a target'

A series of jihadist attacks in Tunisia in 2015 and 2016 left dozens dead. The country has been in a state of emergency since November 2015, when a suicide bombing in Tunis claimed by the Islamic State jihadist group killed 12 presidential guards.

Tunisia also shares a long border with war-torn Libya, where the fall of dictator Moamer Kadhafi in 2011 left a country in chaos.

Many of the armed groups that have profited from the unrest rely on smuggling for much of their income.

Chibani wants other countries to support Tunisia in its efforts to tackle smuggling networks.

He says the current level of international cooperation "does not correspond to the degree of threat that exists in the Mediterranean".

Tunisia's coast needs an electronic surveillance system similar to one being installed on the country's land border with Libya -- as well as "speedboats as good as the ones the traffickers have," Chibani says.

For Saadani, "Tunisia is a target".

"We need to be prepared for every kind of threat," he says.