* Capturing smugglers part of EU's response to migrant crisis

* Warships to operate in high seas, not off Libyan coast

By Robin Emmott

LUXEMBOURG, Sept 3 (Reuters) - The European Union is set to intensify its actions against migrant smugglers in the Mediterranean, the bloc's top diplomat said on Thursday, seeing sufficient political support to start searching and diverting smuggler vessels.

As Europe struggles to respond to its worst refugee crisis in decades, France, Britain and Italy want to stop the smugglers who pack people onto rickety boats for the dangerous journey by sea, part of a wider plan to include taking in asylum seekers.

EU foreign policy chief Federica Mogherini said she saw "a broad consensus" among defence ministers meeting in Luxembourg to go beyond intelligence gathering on smuggler routes in the Mediterranean and to search vessels and make arrests.

EU foreign ministers who meet on Friday must also sign off on the plan, while governments will also need to agree on increasing the number of warships in the Mediterranean, from four today, possibly up to seven.

"I see a broad consensus on the need to start phase two ... that would mean the capture and disposal of vessels," Mogherini said, adding that EU warships could have already intervened on at least 16 occasions over the past 5 weeks to confront smugglers if EU operations had be given the go-ahead to do so.

"This is one fundamental part in our fight against the trafficking organisations. Making their life difficult, if not impossible, is a very important element."

People smugglers typically abandon the laden, flimsy boats several kilometres (miles) off the Libyan coast and let the sea's current take people towards Malta and Italian shores.

EU approval for warships to operate in the high seas would allow vessels to be searched while smugglers are still on board, an EU military official told Reuters.

There are other risks however. With the military mission deployed, traffickers will have to leave the vessels earlier to avoid being arrested, increasing risks for migrants. Engagements with smugglers are also a problem, as traffickers have already opened fire on coast guards in the past few months.

At this stage, warships would not try to capture or destroy boats in Libyan territorial waters, Mogherini said. To do so, the European Union wants to have approval from the United Nations, which Mogherini said she is "actively seeking" or from a Libyan government of national unity, whose establishment is far from guaranteed. (Additional reporting by Francesco Guarascio; editing by Philippa Fletcher)