Nearly two-thirds of tenants have seen their rent increase on their current property at the end of each tenancy agreement, and many are forced to pay additional fees to letting agents to renew their contracts, according to research by Ocean Finance.

Landlords increase rent by an average £84 a month, or £1,008 a year, at the end of each tenancy agreement, the figures show. On top of that, 13% of renters are also hit by charges from letting agents of £117 on average for renewing their tenancies.

The study shows that over half of tenants stay in the same house for five years or more, which could see them paying almost £600 in letting agents’ fees to continue renting their home.

According to the figures from the Office of National Statistics, prices on private rentals increased by 2.1% in the year to March 2015, driven by the buoyant market in London and the South East.

Oceans’s Gareth Shilton said: “The buy-to-let market is booming at the moment, driven partly by the London market, although there are strong hotspots across the country.

“As demand for rented properties continues to outstrip supply, and many people struggle to get on to the housing ladder, landlords are in a strong position to continue to increase rents each time a tenancy agreement ends.

“On top of rental increases, tenants are facing rip-off fees from letting agents, not just to take new tenancy agreements, but also to roll-on an existing tenancy for another six or 12 months.”