A British warship will arrive off the Libyan coast in the next few days in a dramatic attempt to intercept and arrest people smugglers as the flow of migrants trying to cross the Mediterranean for Italy reaches record levels.

The unprecedented and risky intervention comes as Europe steps up its efforts to deal with the growing crisis, which has seen Libya become the primary route for migrants, following the closure of Greece’s borders to refugees last spring. The smugglers last week sent record numbers of migrants to sea, with more than 13,000 people being picked up by charity rescue boats and the Italian coastguard.

At least 100,000 men, women and children have crossed the sea to Italy from north Africa since the start of the year, leading to more than 3,100 deaths from drowning. But fewer than 100 traffickers have been arrested in international waters.

HMS Diamond, a Type-45 destroyer equipped with a 4.5-inch gun, missiles and fast-firing cannon, will join an EU flotilla, Operation Sophia, tasked with catching smugglers at sea. Formal authorisation for the mission was given by Brussels in June. Last week the mission was widened to include intercepting weapons traffickers and training Libya’s coastguard.

But the plan to deploy HMS Diamond was met with scepticism by Crispin Blunt, head of parliament’s powerful foreign affairs committee, who is due to grill British officials about Libya policy later this week.

Blunt said that without Libyan cooperation naval forces could achieve only partial success, with the smugglers having impunity to operate inside coastal waters. “The smugglers are taking advantage of the fact there is no coherent government in Libya,” Blunt told the Observer. “Until there is a political settlement in Libya that encourages a Libyan government to accept assistance in its territorial waters, I fail to see how this can be effective.”

His comments echoed a House of Lords report in May that questioned whether the operation could ever deliver its mandate to prevent people smuggling, with suggestions that the search and rescue operation actually increased the number of crossing attempts. Operation Sophia began last year and until now has concentrated on rescues and intelligence gathering. Its ships arrested 71 smuggler suspects who are now being dealt with by the Italian courts.



HMS Diamond will join more than a dozen EU vessels. Photograph: Chris Ison/PA

The change to targeted interception has been delayed for months as Libya’s new government refused permission for warships to enter its territorial waters, or to provide forces of its own to arrest smugglers on land. The new strategy carries a risk of armed confrontations in the Mediterranean – the Operation Sophia commander, Rear Admiral Enrico Credendino, warned in a leaked report earlier this year that interception missions meant that warships should operate in pairs: one to intercept, the other to return fire.

HMS Diamond joins HMS Enterprise, which last week rescued 700 migrants off Libya, and more than a dozen EU vessels. Enterprise is a survey vessel which began working with GCHQ officers to identify networks in June 2015.

Operation Sophia has used electronic eavesdropping over the past year to build up a picture of migrant smuggling, which is concentrated on the west Libyan coast either side of Tripoli. Mobile phone conversations between gang leaders are tracked, and the Italian-led force is able to identity “blooms” in conversations, indicating that smugglers are poised to send large numbers of migrants to sea.

But in a cat-and-mouse game, the smugglers have changed tactics. After EU navies began seizing wooden smuggling boats, the smugglers have deployed rubber rafts imported from Europe and Turkey. The Operation Sophia report noted one consignment of 20 rubber boats, found in Malta, was allowed to go to Libya because Maltese customs had no powers to seize it. At sea, Credendino says that the smugglers now employ “jackals” – gang members in fishing boats acting as sentinels, tipping off the smuggling boats if they spot naval units in the vicinity.

Libya’s waters are already filling with foreign warships, with the American assault ship USS Wasp mounting airstrikes in support of Libyan forces battling Islamic State at its main base in the coastal town of Sirte. Libyan naval officials are suspicious of western operations in the Mediterranean, with coastguards involved in a confrontation with a Médecins Sans Frontières rescue vessel.