The gender pay gap in Europe ranges from about 100 euros (£79) to 700 euros per month, the ILO report suggested.
In the UK, women earn about 28 per cent less than men on average, the UN body found, reports BBC.
In all the countries studied around the world, a proportion of the pay gap is unexplained, implying discrimination, it said.
"The actual gap varies from about 4 per cent to 36 per cent across all of the 38 countries we looked at," said ILO economist Kristen Sobeck.
In Europe in 2010, the bottom-earning 10 per cent of women workers earned about 100 euros per month less than the bottom 10 per cent of men.
And the top 10 per cent of high-earning women earned close to 700 euros per month less than the top 10 per cent of men.
The ILO looked at education, experience, seniority, work sector, location and work intensity. It found that in about half of the countries studied around the world women had a stronger or better combination of those characteristics, yet were paid substantially less than men.
"For example, in the case of Sweden, what we see is that the overall gap is about 4 per cent, but when you look at the characteristics of women and what they would be paid otherwise, the gap would turn the other way, and women would actually earn about 12 per cent more than men," Ms Sobeck said.
In the UK, about one-third of the pay gap can be explained by men having attributes such as more experience or more seniority, but there is still "a huge gap" that Ms Sobeck said could be due to discrimination.
The ILO recommended a number of ways to overcome the difference in pay between men and women, including wage policies and equality legislation.
The ILO's Global Wage Report also suggested the Asia-Pacific region outperformed the rest of the world when it came to wage growth.
Annual average incomes rose 6 per cent in the region, compared to a global average growth of 2 per cent in 2013.
But despite the big gains, wages in many countries in the region were still much lower than in developed economies.
