SNP ministers have been urged to ensure their flagship plan to bring superfast broadband to every part of Scotland does not become “another lost promise” after a legal challenge.

Scottish Liberal Democrat MPs and MSPs representing the north of the country demanded contingency plans in case most of the R100 programme collapses this year.

The Herald revealed on Sunday that ministers fear a court challenge could see the bulk of the £600m scheme timed out because of a looming EU state aid deadline.

The Government’s legal team told the Court of Session last week that ministers considered it “extremely important” that the challenge be dealt with “in its entirety” by December 31.

READ MORE: Legal challenge could scupper £600million flagship superfast broadband plan

If not, they feared the £384m North Lot, which covers 100,000 premises in the Highlands and Islands, Angus, Aberdeen and Dundee, may no longer “enjoy the protection” of a state aid approval granted to the UK in 2016.

Nicola Sturgeon promised in the SNP manifesto to “deliver 100 per cent superfast broadband coverage for Scotland” by 2021.

However the resulting R100 programme, which is supposed to install 30Mbps+ connections to the remote rural areas, has been beset by delays letting the contracts.

It was not until December that ministers signed deals with BT for the £83m Central and £133m South of Scotland parts, now expected in 2023 and 2024 respectively.

The Government also made BT its preferred bidder for the lucrative North Lot, but a rival bidder, Oxford-based Gigaclear Ltd, then mounted a legal challenge.

It has accused ministers of “manifest error” in the award of the North Lot contract, and asked the court to set it aside, with financial damages as a “secondary remedy”.

With an eight-day hearing pencilled in for October, the four Highland and Island LibDems said they were increasingly concerned about time running out.

In a letter to Connectivity and Islands minister Paul Wheelhouse, they said: “Failure to deliver the R100 programme could have implications for the viability of living and working in the Highlands and Islands.

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“As the current pandemic has graphically illustrated, access to high quality, affordable broadband is an absolute necessity for businesses and households alike.

“Communities across the Highlands & Islands already have the lowest level of broadband and mobile coverage in the country.

“Further delays and the threat of cancellation of the Government’s planned broadband roll out programme is therefore the last thing our constituents and communities need.

“With the government’s scheme bogged down in the courts, and state aid clearance due to run out at the end of the year, Ministers need to spell out their contingency arrangements.

“Our constituents need to know that Ministers have a Plan B and that this won’t simply become another lost promise.”

Mr Wheelhouse, the Minister for Energy, Connectivity and the Islands, said: “Ministers clearly place a very high priority on enabling access to superfast broadband services across all of Scotland, at the earliest opportunity, including in the North Lot area.

"Access to digital connectivity has perhaps never been of greater value than at present, given it has played such a pivotal resilience role during the Coronavirus pandemic.

"Despite the pandemic itself, I am pleased to say that R100 new build will commence in July in the South Lot area and by September in the Central Lot area; this follows survey and design work that was undertaken in the period since both contracts were signed at the turn of the year.

“It would be inappropriate to comment on the legal proceedings in respect of the North Lot while those proceedings are ongoing.”