Overbury’s project to refurbish a London office tower for US bank Citi is set to cost £1.1bn, the client has revealed.

The bank disclosed the extent of its investment in the scheme at 25 Canada Square ahead of US president Donald Trump’s state visit to the UK this week.

In early 2022 Citi unveiled plans to refurbish the 42-storey tower, which is just 20 years old. Reports at the time estimated the cost at £100m.

Now the bank has said it expects to spend 11 times that amount, in a move it said represented its “deep and longstanding commitment to the UK economy”.

It said about two-thirds of the investment would go directly to UK firms and workers.

“This focus on local sourcing has brought in many small and medium-sized enterprises and specialised manufacturers from across the country,” Citi said in a statement.

“At the time of completion, almost 6,000 people will have worked on the project, many of whom live within a 25-mile radius of the building.”

Citi chief client officer David Livingstone added: “This significant investment, which I am pleased to say is progressing on schedule and within budget, underscores Citi’s deep roots and future ambitions in the UK.

“As our second-largest market and a critical financial hub, the UK holds strategic importance to how we serve our clients globally.

“We are proud to reinforce our role both as a financial institution and as a key contributor to economic prosperity and regional development across the country.”

Citi employs about 14,000 people across its UK offices in London, Edinburgh, Belfast and Jersey.

Head of enterprise services and public affairs Edward Skyler said the £1.1bn overhaul of 25 Canada Square was an investment in its people.

“It’s a statement to our thousands of colleagues that they deserve best-in-class workspaces and to our communities that they deserve our lasting commitment,” he added.

Workers are expected to begin moving into the refurbished tower from next spring.

Morgan Sindall subsidiary Overbury has been contacted for comment.