Which? is calling for a review of tenancy agreements used by lettings agents as part of its latest investigation into the sector.

The consumer watchdog tracked the experiences of more than 2,500 tenants as they searched for, secured, lived in and moved on from rented accommodation in England.

It got a housing lawyer to assess some of the tenancy agreements and found unclear language and clauses that could be considered unfair such as making tenants liable for costs that are a landlord’s responsibility or banning tenants from changing gas or electricity supplier.

The research also found supposed evidence of agents pressuring prospective tenants to pay holding deposits or sign contracts without the information needed to make informed decisions.

Millennials were one and a half times more likely to have raised an issue with their lettings agent than other age groups, with one in five claiming they did not receive a written tenancy agreement when they moved into a property.

The report also found tenants were fearful of reporting issues with the property to their landlord.

Half of the respondents said they have ordered, carried out or paid for repairs themselves, with 23% saying they did so to avoid causing problems with their landlord.

Only 44% tenants who felt like making a complaint did so, with 58% fearing repercussions from their landlord.

To combat these issues, Which? is calling for all landlords to be registered with local authorities, with information logged on a publicly available database linked to the existing register of rogue landlords and agents established in April.

It wants to see the creation of an independent regulator for lettings and management agents with a mandatory, legally binding code of practice and strong penalties for rogue operators.

Which? has also suggested a review of tenancy agreements used by letting agents to establish how widespread the use of “unfair, inaccurate or misleading terms and conditions” is, and says action should be taken by the Competition and Markets Authority if required.

Rocio Concha, chief economist for Which?, said: “Our comprehensive look at the experiences of tenants exposes the failings in a rental sector that has failed to keep pace with changes in society that have made renting a long-term reality – rather than just a stepping stone – for millions of people.

“The Government must tackle the issues we have identified in our report head on, to ensure the rental market delivers for consumers.”