Syrian refugees will be brought to Britain more swiftly under a fresh push to tackle the growing crisis announced by the Government.
The UN's refugee agency (UNHCR) will be given extra resources to speed up the resettlement programme, International Development Secretary Justine Greening said.
Divisions in the EU over how to deal with the migrant crisis will be discussed by European leaders at an emergency meeting in Brussels on Wednesday.
Tensions flared between Hungary and Croatia as the governments clashed over how to deal with the influx of thousands of people.
Hungary erected razor-wire fencing along its borders to stop the country being used as one of the major routes into the border-less Schengen area within the European Union.
Hungarian ministers criticised Croatia for sending migrants to its borders, claiming such a move breaches the international law that requires people to be registered in the first country they reach.
Britain has agreed to take 20,000 Syrian refugees over five years from camps surrounding the nation that has been riven by civil war under Bashar Assad's brutal regime and the rise of Islamic State.
The Government will offer extra support to help speed up a scheme that will identify and prioritise the most vulnerable refugees, including survivors of torture and people in need of medical care.
Ms Greening said: "Britain has been supporting millions of people caught up in the brutal Syria conflict right from its start four years ago. We've given more than £1 billion in aid - second only to the United States - for food, shelter, education and health services, helping the victims of this terrible tragedy rebuild their lives in host countries.
"And we will use our expertise to help speed up the resettlement of 20,000 of the most vulnerable Syrian refugees from the region. This is not just morally the right thing to do, but it's also the smart thing to do.
"By taking refugees directly from camps in the region we are ensuring that we reach the most vulnerable, while our aid continues to support others to stay in the region rather than make the perilous journey to Europe."
During a visit to London, US secretary of state John Kerry said America was looking at what more it could do to help alleviate the refugee crisis in Europe.
The US has already ploughed 4.1 billion dollars (£3.6bn) into support for Syrian refugees, he said. "We are committed to try to do more and we are looking at exactly what it will take to do more," he added.
Ms Greening said the first group of refugees under the latest scheme would arrive in Britain over the next week but repeatedly refused to be drawn on how many people would come.
She told BBC One's Andrew Marr Show: "We are going to be bringing the first tranche of people in next week. I'm not going to give you precise numbers."
Pressed for a rough estimate, she said: "I'm not going to give you the numbers."
Asked if it was extraordinary that she could not give a number, Ms Greening replied: "Not really."