British consumer price inflation slowed to 2.8% in April, down from 3.3% in March, official data showed.
Economists had forecast a softer 3.0%, partly due to the fading effect of last year's utility price hikes.
Before the US-Israeli war on Iran began, the Bank of England had expected inflation to near its 2% target. But the energy shock from the war has raised forecasts.
The BoE's most inflationary scenario sees inflation hitting 6.2% early next year.
Finance minister Rachel Reeves is expected to announce new cost-of-living measures on Thursday, including a possible fuel duty freeze.
The ministry is also pushing supermarkets to impose voluntary price caps on staple foods.
Financial markets are pricing in two quarter-point rate hikes by the BoE this year, with a chance of a third.
