Network Rail has sold thousands of railway arches in a £1.5 billion property deal.

Britain’s rail network said that investors Blackstone Group and Telereal Trillium won the bid for the 5,200 properties.

The move has sparked concern among tenants, who believe the sale could lead to higher rents.

A spokesperson from the campaign group, Guardians of the Arches, said: “We continue to dispute whether selling off the whole estate in one job lot is the best way of supporting small businesses and the local economies which rely on them.”

Sir Peter Hendy CBE, the Network Rail chair, said: “This has been a very thorough, detailed and complex process and we are pleased we’re now in a position to announce Telereal Trillium and Blackstone Property Partners as the new owners of the commercial estate.”

“This deal is great news – for tenants it will mean significant commitment and investment, and for passengers and taxpayers it will mean massive, essential improvements without an extra burden on the public purse.”

David Biggs, managing director, Network Rail Property, said: “We are proud to have fostered so many small, independent, diverse businesses and communities across the country and we are confident that these will continue to thrive under the new owners.”

“Ultimately our role is to run, improve and grow the railway, and managing these properties isn’t essential to that. The new owners will invest in and grow the estate, and we can focus on our core business of running the railway.”

Rachael Maskell, the shadow rail secretary, was not excited for the sale and called of the transport secretary to block the sale.

Maskell said the sale would “undermine the financial sustainability of the railway and damage small and medium-sized enterprises across the country”.