The European Union last month suspended naval patrols that had rescued tens of thousands of migrants in the Mediterranean and brought them to Italy, where a populist government now fights the practice.

The EU decision came before Libyan warlord Khalifa Haftar, based in eastern Libya, launched a military offensive two weeks ago on the UN- and EU-backed government in Tripoli.

"I have always argued for the naval assets to remain in the international waters because they have proven to be a very effective deterrent for the (migrant) smugglers and traffickers," Mogherini told the European Parliament.

The naval assets were part of Operation Sophia, which Mogherini said has helped slash migrant arrivals to Europe by more than 80 percent.

"I still hope they (EU countries) can reconsider their decision and decide to redeploy naval assets in the international waters," the former Italian foreign minister said.

Mogherini said it makes sense to send warships to deter not only the migrant smugglers but alsofulfil the "responsibilities we have taken of implementing the UN Security resolutions when it comes to the arms and oil embargo."

Mogherini warned the Members of the European Parliament in Strasbourg that Haftar's military offensive on Tripoli could become a long-running conflict fuelled by illegal weapons.

EU diplomats last month decided to extend Operation Sophia by six months beyond its March 31 expiry date, but without new ship deployments.

Instead, the operation will rely on air missions and close coordination with Libya.

Since its launch in 2015, after a series of tragic shipwrecks, the mission has claimed the arrest of some 150 traffickers, and rescued 45,000 people.

But the election of a far right-populist government in Italy last year changed the fate of the mission, with authorities taking a much harsher stance towards rescued migrants heading for Italian shores.

Italy's anger effectively put an end to rescue operations through Sophia a year ago.

Sources told AFP the decision split the EU's 28 member states, with several countries wondering whether Sophia -- now a naval mission without a navy -- should be halted.

Under the stewardship of far-right Interior Minister Matteo Salvini, Rome has insisted it should not have to carry the burden of dealing with migrants rescued at sea.