David Cameron committed an extra £115 million to tackle the migration crisis as European leaders attempted to overcome bitter divisions to agree a unified response.
The Prime Minister announced the new funds as he arrived at an emergency summit in Brussels.
An extra £100 million will be given to help refugees displaced in camps in countries neighbouring war-ravaged Syria, taking the UK's contribution in the region to £1.1 billion.
In addition the UK will provide £14.5 million towards aid in Europe, the Western Balkans and North Africa, including £2 million for agencies in Libya.
Mr Cameron called on leaders to adopt a "comprehensive approach" and called for more to be done in nations which have seen dramatic exoduses in an effort to stop the thousands entering Europe.
"We need to do more to stabilise the countries and regions from which these people are coming," he said.
"When it comes to Syria, Britain has already given over £1 billion, more than any other country other than the United States.
"And today I can announce we will commit another £100 million, including £40 million to the vital World Food Programme because we must make sure people in refugee camps are properly fed and looked after, not least to help them but also to stop people wanting to make or thinking of making this very, very difficult and very dangerous journey to Europe."
EU leaders are discussing the crisis over a three-course dinner in the Belgian capital the day after interior ministers agreed a controversial plan to relocate 120,000 refugees currently in Italy, Greece and Hungary among the member states.
The scheme provoked a furious row, with four former Eastern bloc states – Slovakia, Romania, Hungary and the Czech Republic – voting against, while Finland abstained.
Britain - which is not required to take part as it is not part of the "borderless" Schengen area - has exercised its right to opt out.
The Prime Minister is expected to use the meeting to press member states to do more to remove economic migrants who are not entitled to refugee status and are coming to Europe in the hope of finding a better way of life.
But the talks could be dominated by rows over the refugee resettlement scheme.
The president of the European Council Donald Tusk, who summoned the meeting, said it was "critical" that member states set aside their differences and agreed on a concrete plan "in place of the arguments and the chaos we have witnessed" in recent weeks.
He warned that the numbers of refugees trying to reach Europe from the Middle East could rise into the millions as the turmoil in the region continued.
However Slovakia's prime minister Robert Fico said his country was not prepared to implement the relocation plan and warned that it could mount a legal challenge through the European Court of Justice.
"We won't implement this decision because we think it can't work," he said. "We always rejected it as nonsense."
Czech prime minister Bohuslav Sobotka, who also opposed the quota scheme, was more conciliatory, saying he would not "escalate tensions" by taking legal action.
"Even though I don't like the use of the quotas, I don't agree with them and we voted against them, Europe must not fall apart over solving the migrant crisis," he said.
European Commission president Jean-Claude Juncker is presenting leaders with a number of measures to be taken.
:: Allowing EU countries to request the deployment of rapid border intervention teams from other member states to provide immediate border guard support in "cases of urgent or exceptional migratory pressure".
:: Restoring free movement in the Schengen zone, in which passport-free movement is allowed in most of the bloc, after some countries reintroduced border controls as they struggled to deal with the crisis.
:: Extra funds of more than £1 billion, including help for affected countries such as Turkey, more cash for Frontex and Europol, the border force and law enforcement agencies and £300 million in humanitarian aid.
The Commission has also announced it is issuing 40 warnings, known as "infringement decisions" against 19 member states for failing to follow asylum laws.
Mr Juncker said: "If you really want to help these people, you have to put your money where your mouth is. Provide us with the funds needed to combat this crisis."