Tenants faced the steepest hikes to private rents for a 17th consecutive month in August, according to official figures charting continued growth across Britain.
The Office for National Statistics (ONS) measured rental prices rising at a rate of 5.5% in the 12 months to August.
That was up from the 5.3% in the year to July.
Wales saw the strongest leap over the annual period – running at 6.5%.
Scotland’s was running at 6% while average prices paid by tenants stood at 5.4% in England, the ONS said.
It added that London’s rate stood at 5.9% – never seen since its data series for the capital began in 2006.
Wider house price data, which lags the rental figures, showed a continued slowdown in the annual rate of growth to just 0.6% UK-wide over the 12 months to July.
Both the house price and rental data reflect the impact of rising borrowing costs.
ONS Head of Housing Market Indices, Aimee North said: “Annual house price inflation, measured using final transaction prices, slowed in July, with negative annual inflation in the South West and London.
“Annual inflation for UK rental prices continues to rise, setting a record high for the seventeenth month in a row.
“Wales is seeing the largest annual price growth nationally, while London rents continue their record-breaking surge.”