* Obama in Greece on last Europe trip as president
* Urges EU to rethink austerity
* Pledges to stand by Greece on debt, refugees

US President Barack Obama, on a visit to Greece, cautioned European leaders on Tuesday against relying only on austerity to tackle the debt woes of struggling economies and also urged greater solidarity with Athens on the migrant issue.
On his last trip to Europe before handing over power to Donald Trump in January, Obama praised Greece's efforts to reform its economy and said the United States stood "shoulder to shoulder" with its Nato ally through the challenges ahead.
Greece, whose economy has shrunk by about a quarter during seven years of grinding recession, hopes Obama will be able to persuade its foreign creditors to restructure some of its debt, which stands at nearly 180% of national output.
"We cannot simply look to austerity as a strategy," Obama said after talks with Greek Prime Minister Alexis Tsipras.
"Our argument has always been that when the economy contracted this fast, when unemployment is this high, that there also has to be a growth agenda to go with it and it is very difficult to imagine the kind of growth strategy that's needed without some debt relief mechanism," Obama said.
Athens signed up to a third economic bailout package of up to €86bn ($93bn) in mid-2015 but says it needs a long-term debt restructuring to exit the crisis - a message repeated on Tuesday by Tsipras, a leftist whose popularity is waning.
Obama is due to visit Germany on Wednesday, the main champion of economic austerity in the euro zone.
'We don't need protectors!'
Not all Greeks were glad to see Obama, the first US president to visit the country since Bill Clinton in 1999.
About 7,000 Greeks gathered at dusk in central Athens to protest against both Obama's visit and the Tsipras government's austerity measures.
"We don't need protectors!" one banner read. An other exclaimed: "Yankees go home!"
The country of 11mn people has also been at the centre of Europe's migrant crisis. More than 60,000 people are stranded in Greece after their onwards journey into Europe was sealed off this year as borders were shut in the Balkans.
"It is important that we don't have any single country bear the entire burden of these challenges," Obama said.
Humanitarian organisations have called on Obama to press the need for a European response to the problem and to demand wealthier countries take in a bigger share of refugees.
"President Obama must use his visit to shine the spotlight not only on abysmal conditions for the tens of thousands of refugees stranded in Greece, but also on the failure of world leaders to adequately address the wider global refugee crisis," said Amnesty International's Europe director, John Dalhuisen.
Obama, who is in Athens until Wednesday afternoon, was staying at a luxury seaside resort on a peninsula south of Athens, less than 15 km from a disused airport that is temporarily housing hundreds of migrants and refugees.
Children played outside the abandoned terminal through washing lines strung with laundry. Some sat on a battered old sofa as Obama's motorcade sped past them.
"We want Obama to come and see us here, how we are living like prisoners," said Hatzi Naser, 42, from Afghanistan, still mired in conflict more than a decade since US forces ousted the Taliban following the 9/11 attacks on the United States.
"He is the reason we are here, because of his army's war. We want him to come and see the filth we are living in."