Many large countries are contributing just a tiny fraction of their "fair share" of the money needed to deal with the dire humanitarian consequences of the Syrian civil war, Oxfam said.
The aid agency singled out governments which have been prominent in the diplomatic battle over Syria for failing to play their part in tackling the refugee crisis - including Russia and France.
And while the US was the biggest single donor - even its £512 million-plus injection was less than two thirds what should be expected, Oxfam said.
Prime Minister David Cameron has spearheaded international demands for developed countries to contribute more - with the UK at present giving one and a half times what should be expected.
Oxfam based its "fair share" figures on the sums being sought by United Nations and other appeals and the relative wealth and income of a group of 28 traditional big donor countries and Middle East states.
The UN's £3 billion appeal for funds for Syria, the largest in its history, remains just 44% funded three months after it was launched. Other international appeals are also struggling, with Oxfam 61% short of its £30.7 million target.
According to the calculations, Russia and Qatar - which have supplied arms to opposing sides in the conflict - have committed just 3% of what they should. New Zealand has committed just 1%, Oxfam said, South Korea 2% and Japan just 17%.
Others failing to get even halfway towards the "fair share" are France (47%), Spain (46%), Greece and Italy (42%), Portugal (39%), Switzerland and the United Arab Emirates (33%).
They include a third of the members of the Development Assistance Committee of the Organisation for Economic Co-operation and Development.
Only eight of the countries were gauged to be giving sufficient funds, with Kuwait the most generous at more than four and a half times its fair share (461%). Luxembourg (232%), Denmark (230%), Saudi Arabia (187%), the United Kingdom (154%), Norway (134%) and Sweden (132%) helped make up that list.