A BBC project to rebuild the set of EastEnders is expected to cost £27 million more than planned, sparking concerns over licence fee payers' value for money.

Reconstruction of the soap opera set is part of wider improvement works at BBC Elstree, in Borehamwood, which are set to cost the public broadcaster £86 million in total, with a completion date now two and a half years late.

Lack of expertise, over-optimism regarding costs and delays in construction have led to a 45 per cent budget increase for the project, according to the National Audit Office (NAO).

Auditors concluded that the BBC cannot provide value for money on the wider project - termed E20 - which will see the 1984 set of the soap rebuilt and expanded.

However, the report added: "As the (EastEnders) Front Lot construction only started in October 2018 and the Back Lot is at an early design stage, it is not yet possible to conclude on the value for money of the latest programme plan."

The original set of EastEnders was intended to be used for two years, but has been in use for 34. This has led to problems with health and safety, continual investment in refurbishments, and the inability to shoot in high-definition due to the decaying set.

In 2015 the rebuild - using real brickwork to create the set rather than facades - was estimated to cost £59 million, and the project was to be completed by August this year.

A budget was then approved for the increased amount to £62 million, and a delay of 26 months forecast in 2016.

A new EastEnders set is expected to be delivered in 2023. It will include a Front Lot replicating Albert Square and the traditional set, and Back Lot, made to look more like the streets of 21st century London.

The BBC said in a statement: "The set of EastEnders was built in 1984 and only intended for use for two years. Over 30 years later, the show remains one of the BBC's flagship programmes and yet is filming from a set that is no longer fit for purpose.

"The new set will be suitable for HD filming for the first time and extend Walford to better reflect modern East End London.

"It's a large, complex project which has already delivered many other vital improvements at BBC Elstree Centre, but like any building work of this scale there have been challenges on the way, including construction market issues beyond our control and from working on a brownfield site.

"As the NAO recognises, we've already made improvements and are keeping the project under close scrutiny."