The Latest on Europe's response to the migrant crisis (all times local):

11:45 a.m.

Prime Minister David Cameron will deploy another warship off the coast of Libya to help stop the trafficking of people and arms.

Cameron told leaders at the Group of Seven summit in Japan on that Britain was ready to crack down on smuggling. Four U.K. vessels are already involved.

In a tweet on Friday, Cameron said: "Once all relevant permissions are in place, I will deploy a naval warship to the south central Mediterranean to combat arms trafficking."

Libya's new U.N.-brokered government has asked for help in improving its coastal maritime operations and it is thought it will soon request that international ships also operate in territorial waters.

Some smugglers have sent migrants out in boats with only enough fuel to get them past the Libyan coast, leaving them to be drift until being spotted by EU ships.

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11:40 a.m.

The U.N. refugee agency is expressing concerns that migrants and refugees who have been moved to several sites with "sub-standard conditions" after being evacuated from a makeshift camp near Greece's border town of Idomeni.

UNHCR says some evacuees were taken to "derelict warehouses and factories" with "insufficient" supplies of food, water, toilets, showers and electricity.

At a briefing in Geneva on Friday, UNHCR spokeswoman Melissa Fleming called on Greek authorities, with financial support from the European Union, to find "better alternatives quickly" for some of those moved out from Idomeni, which is near the Macedonian border.

The agency said in a statement Friday that it was concerned that some families are being separated during their transfer from Idomeni, but noted that the evacuations took place "without the use of force."