Europe's migrant crisis is set to be in focus at the UN with Secretary-General Ban Ki-moon seeking to muster a global response to the exodus of vast numbers of people from Syria and elsewhere.
The UN chief opened the General Assembly in New York this week with a call to Europe "to do more" and appealing to the international community to tackle the source of the problem.
"We should not be building fences or walls, but above all we must look at root causes, in countries of origin," said Ban, due on Wednesday to host a meeting of around 70 countries on the crisis in New York.
Syria's four years of civil war, another hot topic in New York this week, has left more than 240,000 people dead. More than four million have left the country, and millions more are internally displaced.
According to the latest figures from the UN refugee agency on Wednesday, Syrians made up 55 per cent of the 521,000 migrants who have crossed the Mediterranean bound for Europe this year to date.
Many others come from Iraq which, like Syria, has seen Islamic State extremists overrun massive areas, and from Afghanistan and other hotspots. Nearly 3000 died or went missing in the often treacherous crossing.
In the latest reminder of the dangers, Greek police said on Wednesday that a woman and a child drowned off the island of Lesbos after their boat sank, although 45 others were rescued.
An Eritrean man was also killed by a train near the entrance to the Channel Tunnel early on Wednesday in France near Calais, where about 3000 migrants are camped, an official said, the 13th such death there since June.
The huge influx, Europe's biggest since World War II, has exposed deep rifts in the continent about where the newcomers should go and what should be done to stem the flow.
Plans to share out 160,000 migrants throughout the 28-nation EU using mandatory quotas are opposed by several member states, and mooted "hot spots" on Europe's borders are controversial.
Reflecting the scale of the problem, the G7 group of leading economies and Gulf states pledged US$1.8 billion (NZ$2.81 billion) in funding on Tuesday for UN aid agencies helping Syrian refugees, while Japan committed $US1.5 billion.
"The cause of this tragedy is the fear of violence and terrorism, and terror of poverty," Japanese Prime Minister Shinzo Abe said in New York.
"The world must co-operate in order for them to find a way to escape poverty."
The first destination for many crossing the Med is Greece. Mostly the migrants then leave and travel up through the western Balkans hoping to make it to richer places like Germany or Sweden.
A particular source of EU friction is Hungary, which lies at the end of this Balkans route. It has sealed its border with Serbia and is threatening to follow suit with Croatia, currently the main crossing point.
Prime Minister Viktor Orban says that with Greece and the EU as a whole failing to do its job and Germany encouraging people to keep coming, Budapest has little option.
He has also said that the influx of Muslims poses a threat to "Christian" Europe and that the new arrivals, because they left the relative safety of camps outside Syria, are not refugees but economic migrants.
On the eve of Wednesday's talks, Hungary's foreign minister urged the UN to set global quotas on accepting migrants, saying it was unfair for Europe to take so many.
"We suggest that all major players should bear some burden. We should introduce some world quotas," Peter Szijjarto told reporters.
More than 6600 people entered Hungary on Tuesday, mostly from Croatia, police said. Buses were taking them onwards to the Austrian border, while workers were constructing two new "transit zones", AFP reporters said.
Countries need to "come to an understanding that migration is a mega-trend of our century and depoliticise it", William Swing, the head of the International Organisation for Migration told AFP.