UK inflation hit its highest in more than five years in August as households paid more for fuel and clothing.
This will complicate the Bank of England's job this week of explaining why it is not raising interest rates.
The fall in the value of the pound since last year's Brexit vote helped drive the biggest rise in clothing prices since the consumer price index was launched in 1997, up by 4.6% in annual terms, and rising global oil costs also hit.
UK consumer prices overall increased by 2.9% compared with a year earlier, the Office for National Statistics said.
This was up from 2.6% in July and above the median forecast in a Reuters poll of economists for a rise of 2.8%. That took the CPI back to its level in May.
Sterling hit a four-week high against the euro after the data as investors priced in a greater chance of the Bank of England's Monetary Policy Committee raising interest rates for the first time since before the global financial crisis a decade ago, and British government bond prices fell.
Analysts said that the Bank of England had been expecting inflation of 2.7% in August and while no change in rates was likely this week, the inflation reading was a challenge for the central bank.
It is worried that uncertainty about Brexit will hurt the economy and has so far held off from raising rates to avoid adding to a slowdown in growth seen in the first half of 2017.
The Bank of England targets 2% inflation, but most of its policymakers have voted to keep rates at their all-time low of 0.25% as Britain prepares for the challenge of leaving the European Union in 2019.
The Bank of England said last month it expects inflation to reach about 3% in October, much of it due to the fall in the value of the pound since the Brexit vote.
A further recent fall in the pound against the euro is likely to keep pressure on British inflation for longer than the Bank of England forecast in August.
Today's data hinted at some future price pressure as the costs of raw materials for manufacturers and of goods leaving factories increased slightly.
UK factory gate prices rose by an annual 3.4%, the first increase in the rate since February. Economists in a Reuters poll had expected growth of 3.1%.
Prices paid by factories for materials and energy rose by 7.6%.
The ONS said excluding oil prices and other volatile components such as food, core consumer price inflation rose by 2.7%, stronger than economists' expectations of 2.5%.