Image caption As a percentage of the overall population, Thais were the most generous in donating money

The US has been rated as the world's most charitable country in 2011 by the Charities Aid Foundation's (CAF) World Giving Index, up from fifth in 2010.

The Irish Republic came second, then Australia, New Zealand and the UK.

The survey suggested more people were likely to perform charitable acts this year compared with 2010, but less likely to give money.

The CAF said the "global economic crisis" was the likely reason for the slight fall in charitable donations.

The group said the richest countries were not necessarily the most likely to give to charity - only five nations that are in the World Bank's top 20 economies by GDP appear in the latest CAF giving index top 20.

In terms of percentage of population, Thailand was the most generous, with 85% of Thais making regular charitable contributions. The UK was the second most generous, with 79% regularly giving to charity.

Countries were ranked in terms of the monetary donations and charitable acts of their people.