The Consumer Prices Index remained at 4.5% in May, unchanged from April, show the latest figures from the Office for National Statistics.
The Retail Prices Index, which includes mortgage interest payments also remained unchanged at 5.2%.
The ONS says although unchanged overall, there were significant upward and downward pressures on CPI annual inflation between April and May.
The main downward pressure to annual inflation came from air transport where thetiming of Easter had a significant impact on the April to May movement.
The main upward pressures to annual inflation came from a variety of food products.