A British battleship is set to be deployed into Libyan waters to tackle human smuggling and "assist in the interception of arms" which could fall into the hands of the Islamic State (Isis). David Cameron is expected to announce the move to G7 leaders today (27 May).

It comes as the UK government expects a formal request for help from Libyan authorities "fairly swiftly". The vessel would join four other Navy ships operating close to Libyan waters as part of a Nato mission.

Earlier this week the UN-backed unity government in Tripoli asked the EU for more assistance in training its navy and coastguard to take down people smugglers. The prime minister looks to be leading the push for increased involvement in the region.

"[The prime minister will] make the argument it is a global challenge requiring a comprehensive solution, reiterate our determination to work with the Libyan government and help them build the capacity of their coastguard to help them intercept boats off the Libyan coast," a Downing Street spokesman was quoted by Reuters as saying.

He added: "We will now take an active leadership role in that process. Four military planners have deployed to Rome this week to the HQ of Operation Sophia, the naval mission in the Med, where they will work with other EU colleagues to agree a plan going forward for the Libyan coastguard.

"Once that is established we will then send a training team to assist the Libyan authorities in improving their coastguard maritime operations. Then, once the relevant UN security resolutions are in place, we intend to deploy a navy warship to the region to assist in the interception of arms and human smuggling." While ministers are willing to support Libya, a UN Security Council resolution would be required before going after arms traffickers.

While Operation Sophia conducts missions in international waters close to Libya, it is still too far out to take on boats used by people smugglers and arms traffickers, or divert migrants seeking to reach Europe. Officials are hoping that an expansion of Operation Sophia will help thwart people-trafficking.