The number of people in work has fallen by 14,000, the biggest reduction in over two years, figures have shown.
Employment was just over 32 million in the quarter to September after the largest three-monthly fall since April-June 2015.
Other figures showed that the number of people classed as economically inactive increased by 117,000 to 8.8 million, the biggest rise in over seven years.
The number includes those on long-term sick leave, looking after a relative, taking early redundancy or who have given up looking for work.
Unemployment fell by 59,000 to 1.4 million, the lowest figure in over 12 years, giving a jobless rate of 4.3%, the Office for National Statistics (ONS) reported.
Average earnings increased by 2.2% in the year to September, down by 0.1% on the previous month and by 0.3% on a year ago.
Average weekly earnings in real terms, adjusted for inflation, fell by 0.4% compared with a year ago.
ONS statistician Matt Hughes said: "After two years of almost uninterrupted growth, employment has declined slightly. However, it remains higher than it was this time last year, and as always we would caution people against reading too much into one quarter's data."
Other figures showed that the number of EU nationals working in the UK increased by 112,000 to 2.38 million in the latest quarter compared with a year ago, while non-EU nationals fell by 23,000 to 1.21 million.
The ONS said the number of non-UK nationals was still rising, albeit more slowly than in the last couple of years.
The employment rate for EU nationals is 81.6%, compared with 75.3% for UK nationals.
Productivity increased by 0.9% in the latest three months following two quarters of falling output.
ONS head of productivity Philip Wales said: "While the latest quarterly growth rate is the strongest for six years, over the last 12 months productivity has grown by just 0.6%.
"The medium-term picture continues to be one of productivity growing but at a much slower rate than seen before the financial crisis."
Employment minister Damian Hinds said: "The strength of the economy is driving an increase in full-time, permanent jobs and a near-record number of people are now in work thanks to the Government's welfare reforms.
"When unemployment fell to 5% early last year, many people thought it couldn't get much lower, and yet it now stands at 4.3%."
TUC general secretary Frances O'Grady said: "This is the seventh month in a row that prices have risen faster than wages, but ministers are still standing on the sidelines.
"Running the economy is not a spectator sport - the Chancellor must have a game plan to give Britain a pay rise in next week's Budget."