Developers behind the £850 million development on the site of the St James shopping centre in Edinburgh are trying to block plans for a new film studio on the outskirts of the city amid fears it could undermine its own project.

The Scotsman has reported that real estate firm Henderson, which is due to start work the project within months, has lodged a formal objection against a £150 million studio development planned for Straiton which it describes as a front for a retail development.

Plans submitted to Midlothian Council for the development include an unspecified retail element.

Henderson, which has predicted its project will be worth £25m a year to the economy, has raised fears the studio scheme will lead to a further extension of the nearby Straiton Retail Park and undermine the “vitality and viability” of shops in Edinburgh city centre.

More than 3000 jobs are promised with the £850m St James development, which will feature around 850,000 sq ft of retail space, along with a 210-bed hotel, 250 homes and 30 restaurants.

The proposed studio was announced in August 2014 by a consortium of property and film industry figures, but the plans are yet to win official backing. The Pentland Studios scheme would involve the creation of six separate sound stages up to 70 feet tall, as well as a 50,000 sq ft creative industries hub and 50,000 sq ft of workshops on an 86-acre site.

The Scottish Government is to rule on the studio development after the council failed to reach a decision.

Acting on behalf of Henderson, agents GVA Grimley say the masterplan published by film studio developer PSL Land Ltd shows that more than half a million sq ft of new retail space could be created.

Its letter of protest says extending the number of shops in the Straiton area would “undoubtedly have a negative impact” on Edinburgh city centre and points out that the retail, office and commercial element of the scheme is in “close proximity to Straiton Retail Park.”

Referring to the St James scheme, it adds: “Given the significant scale of this investment proposal and wider benefits that could result for the entire city region, it is important that a strong planning policy framework in place to protest the city centre to maintain investor confidence.

“Our client has legitimate concerns about the (studio) development, its potential to be used as a further extension to the retail park and the resulting adverse impacts.”

PSL director Jim O’Donnell said he was unconcerned about the objection as retail was not part of the proposed studio development and suggested the letter was “a standard form”.