* Oxfam says richest 1 pct of own more than other 99 pct

* Edelman survey shows widening trust gap with politicians

* Inequalities blamed for rise of populism in U.S., Europe

* Obama acknowledges more wealth concentrated at "very top"

By Ben Hirschler and Noah Barkin

DAVOS, Switzerland, Jan 18 (Reuters) - Politicians and business leaders gathering in the Swiss Alps this week face an increasingly divided world, with the poor falling further behind the super-rich and political fissures in the United States, Europe and the Middle East running deeper than at any time in decades.

Just 62 people, 53 of them men, own as much wealth as the poorest half of the entire world population and the richest 1 percent own more than the other 99 percent put together, anti-poverty charity Oxfam said on Monday.

Significantly, the wealth gap is widening faster than anyone anticipated, with the 1 percent overtaking the rest one year earlier than Oxfam had predicted only a year ago.

Rising inequality and a widening trust gap between people and their political leaders are big challenges for the global elite as they converge on Davos for the annual World Economic Forum, which runs from Jan. 20 to 23.

But the divisions go far beyond those that exist between the haves and have-nots. In the Middle East, the divide between Shi'ites and Sunnis has reached crisis point, with Iran and Saudi Arabia jostling openly for influence in a region reeling from war and the barbarism of Islamic extremists.

The conflicts there have spilled over into Europe, causing deep ideological rifts over how to handle the worst refugee crisis since World War Two and - with Britain threatening to leave the European Union - raising doubts about the future of Europe's six-decade push towards ever closer integration.

The shock emergence of Donald Trump as the front-runner for the Republican presidential nomination has exposed a gaping political divide in the United States, stirring anxiety among Washington's allies at a time of global turmoil.

Among the key figures in Davos, will be U.S. Vice President Joe Biden, Secretary of State John Kerry, Israeli Prime Minister Benjamin Netanyahu and the foreign ministers of both Iran and Saudi Arabia.

Canada's new Prime Minister Justin Trudeau will be on hand, as will Britain's David Cameron and Mario Draghi at a time when a new transatlantic monetary policy divide is opening up between his loosening European Central Bank and a tightening U.S. Federal Reserve.

Celebrities will also be out in force, including film stars Leonardo Di Caprio and Kevin Spacey.