One in five properties in England and Wales have seen rents rise 10% or more this year, according to latest data from the Office of National Statistics (ONS).
The figure was one in four in London where rents have soared as landlords sell up and tenants multiply.
The ONS data look at prices and behaviour in the private rental sector in England and Wales.
ONS researchers check rental prices on average every 12 months in England and nine months in Wales.
They found that rents were more likely to have been hiked in England and Wales since the last check than they were a year earlier (63% in England and 44% in Wales).
In instances where rents had risen, they were up 11.3% in Wales and in England 9.7%. A year earlier it was 10.5% in Wales and 8.4% in England, the ONS said.
In England, rents are most likely to have risen in London (77%), and least likely in the North West (42%).
However, those rents that did rise in the North West did so more than anywhere else – at an average of 12.3%.
Sarah Coles, head of personal finance, Hargreaves Lansdown, said: “The rental market is getting squeezed on all sides. Landlords are under rising pressure. They face tougher rules that mean they pay more tax on the way in, as they go along and then when they sell. More rights for renters means landlord costs are increasing, which means they make less money.”