Portuguese consumer prices spiked 8% year-on-year in May, at their fastest pace since February 1993, after rising 7.2% in April, flash data from the National Statistics Institute (INE) showed on Tuesday.
Core inflation, which strips out volatile food and energy prices, clocked 5.6% year-on-year, its highest level since October 1994.
On a monthly basis, consumer prices in Portugal rose 1%, slowing down after a 2.2% increase the previous month.
Sanctions on Russia following its invasion of Ukraine last month have pushed energy prices to record highs across Europe, stoking overall inflation and sapping confidence.
(Reporting by Joao Vicente and Andrei Khalip)