UK retailers were boosted by Easter falling at a later date this year, with like-for-like sales rising 5.6% compared to the same period a year ago.
The British Retail Consortium (BRC) said total retail sales were up 6.3%, the biggest increase recorded in six years.
This was mainly due to Easter falling in mid-April this year compared to late March in 2016, while rising prices due to the fall in the value of the pound was another factor.
Total food and drink sales rose 3.6% in the three months to April, while non-food sales were up 0.7%.
"The positive distortion from the timing of Easter was largely responsible for the month's growth and looking to the longer-term signs of a slowdown, the outlook isn't as rosy," BRC chief executive Helen Dickinson said.
"Although today's figures do indicate that consumers are still willing to spend, with a cocktail of rising costs and slowing wage growth as the backdrop, conditions for consumers will get tougher.
"The next government needs to deliver a plan that puts consumers first in its economic policies and the forthcoming Brexit negotiations."
Paul Martin, head of retail at KPMG, said while the figures appeared positive for supermarkets, they should be taken with a "hefty pinch of salt" as grocers' margins are under significant pressure.
"April's sales provided a brief period of respite for retailers following a relentless start to the year," he said. "Retailers need to ensure that this month's boost doesn't lull them into a false sense of security.
"The retail landscape is changing fast and as such, agility and the ability to manage costs will remain critical."
The UK's official inflation rate stood at 2.3% in March – above the Bank of England's 2% target.
The headline inflation rate is expected to climb further in the coming months as the weaker pound pushes up import prices.