The consumer prices index increased at a higher than expected rate of 3.6% in June, the Office for National Statistics (ONS) revealed. Motor fuels are the main factor behind the upward shift in CPI from 3.4% in May, according to the ONS. The price of a litre of petrol is not rising – it fell by 0.5p between May and June. But it was plunging this time last year, so the smaller monthly decline puts upward pressure on inflation. Food prices have also continued to be strong, rising at an annual rate of 4.5% – the fastest since February last year.