Splits within the EU on the relocation of 120,000 migrants have been further exposed as leaders begin an emergency meeting in Brussels.

Slovakia is launching a legal challenge to mandatory quotas that were passed in a majority vote on Tuesday.

Meanwhile, Hungary's prime minister has proposed a radical budgetary revamp to raise funds.

The summit will focus on tightening EU borders and aiding neighbours of Syria, from where many migrants come.

Draft proposals seen by the BBC, that will be discussed at the summit, include:

-donating at least €1bn (£700m, $1.1bn) to UN aid agencies to help Syrian refugees
-sending more staff to shore up Europe's external borders and in the western Balkans, through which many migrants pass
-giving more support to Lebanon, Turkey, Jordan and other countries neighbouring Syria

European Council President Donald Tusk called for "a concrete plan" to secure the EU's external borders, "in place of the arguments and the chaos we have witnessed in the past weeks".

As she arrived at the summit, Lithuania's President Dalia Grybauskaite said it was "not a lack of European unity, but a lack of European wisdom" that had led to this point.

On arriving, British Prime Minister David Cameron said the UK would be giving another £100m ($152m) to help Syrian refugees, including £40m towards the World Food Programme.

"We need to do more to stabilise the countries and the regions from which these people are coming," he said.

The UK has opted against taking part in the relocation scheme and has its own plan to resettle migrants directly from Syrian refugee camps.

The scale of the problem was highlighted again on Wednesday when Croatia revealed that 44,000 migrants - including 8,750 on Tuesday - had arrived there since Hungary completed a fence along its border with Serbia last week.

BBC