Figures from SocialBakers have shown that the number of UK Facebook users fell by 600,000 in December: a 1.86 per cent drop.
Ranked at number six in the territories with the largest Facebook user base, the UK was the only country in the top 10 to show a decline last month.
The SocialBakers research also found that 33 million unique users accessed Facebook in the UK in December, which comScore describes as 53 per cent market saturation; second only to the US, which has a 54 per cent saturation rate and 169 million unique users per month.