The main investor behind a boom in high-rise apartments in the centre of Cardiff has claimed the developments could bring the city’s rising rents down.

Finance company Legal & General is building 1,000 flats to rent in the Welsh capital.

But with some of its one-bedroom apartments costing £1,300 per month, a letting agency has warned renters could be priced out of the market.

Private rents in Wales have risen by 8.5% over the past year, while in Cardiff they have increased by more than 9%, according to recent data from the ONS.

Cardiff is following in the footsteps of cities like Manchester and Liverpool and seeing a major growth in so-called build-to-rent accommodation, which are apartment blocks owned by investment companies that are only available to rent.

They typically have on-site gyms, communal living spaces and concierge reception areas.

Around 1,000 flats of this kind have been built in Cardiff in recent years and nearly 3,000 more are on the way, according to property consultancy Bidwells.

They said the average monthly rent of a one-bed in Cardiff’s new build-to-rent market was £1,297 per month, compared to £944 in the traditional market.

Legal & General claim that by increasing the supply of properties on the rental market, prices will become more affordable.

“With huge amounts of supply all coming in at one time, we are controlling and limiting rents going up in the city,” said Dan Batterton, the company’s head of residential.

But Jon Hooper-Nash, lettings director at Jeffrey Ross estate agents, is sceptical.

“It is classic GCSE economics: supply and demand, but the rents they are asking for are already much more expensive than what they are up against,” said Mr Hooper-Nash.

“So I don’t quite understand the narrative that they are going to bring rents down, when they have put them up.”

Legal & General, which has 30 residential developments across the UK, already owns one block in Cardiff with around 300 apartments called Wood Street House, which it said was full.

It said another development with more than 700 apartments on the site of the former Brains brewery would come on stream next year.

“People have slowly moved out of city centres because they have not been particularly nice places to live but we need to use the land we have got better, otherwise we have to start expanding our cities,” said Mr Batterton.

“We are taking brownfield land in the middle of our city centres, building homes on them and that is bringing people back.

“People are using the high street, the restaurants and bars because that is where they live.”

Asked whether the rents were too high for the local market, Mr Batterton said rents in the new site would be lower.

“We cannot just be high-end if we have 1,000 apartments in the city centre of Cardiff, we have to be attractive to as wide a range of demographics and wages as we possibly can.”

But Mr Hooper-Nash said the rents of the new apartments would have to come down substantially to be affordable.

“We deal with hundreds of tenants every week. In 12 months it may be different, but the people we see, the private rental tenants in Cardiff, what they can typically afford is not that,” he said.

“Unless a change is happening I don’t see how they’re going to work.”

So what do renters make of the new developments?

Eden Cronin, 27, from Cardiff, welcomed any increase in the supply of rental accommodation.

“It took us ages to find a place,” she said.

“We found when we were looking or going to places, it had already been taken or there had been three viewings before us. It was almost like a race.”

What did she think of £1,300 for a one-bed apartment?

“It’s expensive, especially as it’s not London.

“I would expect something quite big, spacious with a garden, a driveway or somewhere to have a car.”

Alejandra Escamilla, 26, from Cardiff, said she was currently paying £900 a month to rent a one-bed apartment and that was “within [her] comfort zone”.

“It’s a one-bed apartment with a shared garden and the building is quite new. No bills are included,” she said.

“I am expecting rents to go up actually but I am planning on moving out of the city. That will be cheaper.”

Fergus Thomas, 31, from Abergavenny, cast doubt on the investor’s claim that rents could be brought under control.

“I think it’s probably unrealistic,” he said.

“I have rented for quite a few years and every time I feel it gets harder to find something, and every time it feels more expensive.

“There is too much money to be made and too many people looking to rent a place so I don’t think they’ll come down.”

Ben Gaffiero, 28, and his partner Pratibha Zala, 27, live in a build-to-rent apartment block called Copper Works which has an on-site gym, concierge reception and roof terrace.

They pay £1,100 a month for a one-bed apartment with bills on top and said it felt like living in a hotel.

“I lived in a different place that was about £800 a month and that was disgusting, so comparing that to there I would say it is worth it. At least it’s hygienic and a place that is good to live for a human being,” said Ben.

“It gives us a different standard of living,” added Pratibha.