Black Friday deals boosted British retail sales last month, according to official data published Thursday, as inflationary pressures look set to lift prices up in the coming months.

Overall retail sales including fuel purchases rose by 5.9% in November compared with the same period last year, Britain's Office for National Statistics (ONS) said, down from October's 7.2% pace. Month-on-month sales increased by 0.2%, the ONS said.

The FTSE 350 General Retailers Index was marginally down at 2,528.63 at 10:30 GMT. The index, which includes some of the U.K.'s biggest retailers, has lost more than 15% since the beginning of the year. In comparison, the FTSE 100 index, London's main market, has added more than 11% since the start of 2016.

"Retailers saw continued growth in the run up to Christmas. Department stores and household goods stores had a particularly strong month, especially in sales of electronic goods, boosted by Black Friday deals," ONS Senior Statistician Kate Davies said in a statement. "Fuel sales, however, were at their lowest levels for two years as prices increased at the fastest rate since 2011."

The data show that average store prices increased by 0.1% in November compared with the same time period last year. Although not a huge amount, this was the first year-on-year price increase since June 2014.

The ONS said the biggest contributor to the price increase was fuel.

The rise in prices were in line with the latest consumer price index data released on Tuesday.

Consumer prices rose by a faster-than-expected 1.2% in November from the same period last year, ahead of analysts' forecasts of a 1.1% rise and 3 basis points higher than the final October reading of 0.9%, the ONS said. So-called core inflation, which strips out volatile prices for food and energy, accelerated at a faster-than-expected 1.4% pace, the ONS said.

Online sales increased by 24.9% in November compared with the same month last year and were up 3% from October 2016.