Morrisons, the UK's fourth-biggest supermarket group, said political and economic uncertainty had weighed on its first-quarter growth.
It also warned that it faced a tough comparative over the next three months.
The group, which trails market leader Tesco, Sainsbury's and Walmart's Asda in annual sales, said its like-for-like sales, excluding fuel, rose 2.3% in the 13 weeks to May 5, its fiscal first quarter.
That was slightly below analysts' average forecast for growth of 2.5%, and below growth of 3.8% in the previous quarter.
Morrisons said the political and economic uncertainty was continuing to impact consumer confidence and cautioned that comparative numbers are tough in its second quarter as the group will be up against last year's favourable summer weather and the soccer World Cup.
In the first quarter, like-for-like retail sales were up 0.2%, while wholesale rose by 2.1%.
Morrisons' update chimed with recent monthly industry data which has shown it lagging a strengthening Tesco, matching Asda and outperforming Sainsbury's.
Before today's update, analysts' consensus forecast for 2019-20 was an underlying pretax profit of £435m, up from £406m made in 2018-19.
