European leaders are continuing to struggle to come to terms with an unprecedented refugee crisis with Austria and Germany throwing open their borders on the weekend.

The move came after Hungary - the main entry point into Europe's "borderless" Schengen zone - abandoned its attempts to prevent migrants and refugees from leaving by stopping them from boarding trains and instead provided buses to take them to the border. It came after more than a thousand refugees decided to walk to the border from the Hungarian capital Budapest rather than wait for trains.

ARRIVAL IN EUROPE: Syrian children and other refugees with blankets provided by Austrian volunteers after crossing into Austria. PICTURE: © UNHCR/M. Henley

"Europe cannot go on responding to this crisis with a piecemeal or incremental approach. No country can do it alone and no country can refuse to do its part."

- António Guterres, UN High Commissioner for Refugees

The UN refugee agency, UNHCR, welcomed the decision of Austria and Germany, describing it as "political leadership based on humanitarian values".

The organisation also praised civil society groups and the Austrian and German citizens who are welcoming and providing aid to the refugees and migrants as they enter the country.

But they have warned that such a solution is not a sustainable solution. António Guterres, the UN High Commissioner for Refugees, has said the biggest influx of refugees into Europe for decades required a "massive common effort" and has called for a rethinking of the fragmented approach taken to the crisis by European nations to date.

"Europe cannot go on responding to this crisis with a piecemeal or incremental approach," he said last week. "No country can do it alone and no country can refuse to do its part."

The UN says more than 300,000 people have risked their lives to cross the Mediterranean from North Africa and the Middle East so far this year.

"Over 2,600 didn't survive the dangerous crossing, including three-year-old Aylan, whose photo has just stirred the hearts of the world public," said Mr Guterres. He said the EU now has "no choice" but to "mobilise full force" around this crisis and implement a common strategy based on "responsibility, solidarity and trust".

This includes recognising that the crisis is primarily a refugee issue with the vast majority of those people arriving in Greece coming from conflict zones like Syria, Iraq and Afghanistan, the implementation of a relocation program involving all EU states for those people found to be genuine refugees and quick return of those who are not with full respect of their human rights. 

He said that while more international cooperation is required to crackdown on people smugglers, such efforts will be fruitless without opening up more opportunities for refugees to come legally to Europe and find safety on arrival. He said European nations as well as governments in other regions must make "fundamental changes" to allow for larger resettlement and humanitarian admission quotas, expanded visa and sponsorship programs, scholarships and other ways to legally enter Europe. 

But Mr Guterres also noted that the "massive flow" of people would not stop until the root causes of the issue were addressed.

Following comments that there was no legal limit to the number of asylum seekers Germany will take in amid expectations it will take in at least 800,000 this year, German Chancellor Angela Merkel last week called for mandatory refugee intake quotas for all EU countries.

That view has met with a range of responses from other EU leaders. France has supported the idea of some sort of mandatory intake system while UK Prime Minister David Cameron has said the UK would "fulfil our moral responsibilities" and would provide resettlement to "thousands" of Syrian refugees. European leaders will be meeting on 14th September to discuss the issue.

Meanwhile in Australia, Prime Minister Tony Abbott announced on Sunday that the country will take more refugees from Syria - increasing the proportion of Syrians among our total refugee quota - but would not increase the overall quota. He said Australia had always been a "good global citizen" and its response was "doing the right thing by the world".

But a number of groups have called for the country's humanitarian intake to be increased. Among them is the Australian Christian Lobby which has called for a doubling of the intake to 27,400.

Lyle Shelton, the ACL's managing director, said that while the government was right to protect "persecuted religious minorities" by increasing the number of Syrian asylum seekers the country will take, such a response was "inadequate". "We recognise that Australia can't solve this crisis but it can shoulder more of the burden, given we are a wealthy country with capacity, particularly in regional areas".

Phil Glendenning, president of the Refugee Council of Australia, told ABC radio this morning that Australia could take "considerably more" asylum seekers than what the Prime Minister was advocating. He said the Europeans - in particular Germany - was showing a "much clearer way in exercising not just compassion but their international obligations".