A leading candidate to take over the ScotRail franchise has brushed off concerns over the commercial viability of the Borders Railway project, saying that it will present a "suite of ideas" about how to incorporate the expected loss-making new service within a profitable network.

Abellio, a subsidiary of Netherlands Rail, claims to have established an early lead in what will be a closely-fought battle to win the 10-year franchise to run 85% of the Scottish rail network. Its bid is based on its previous experience of running a "social railway" which boosts passenger numbers.

Mike Connelly, Abellio's stakeholder relations manager, told the Sunday Herald that rail experts' fears about the challenges of factoring a commercially insecure extension into the already complex franchise negotiations were exaggerated.

He noted that other recent network extensions, such as Stirling-Alloa and Airdrie-Bathgate, had been easily incorporated by the current franchisee, First Group, and that the profile of the new railway, which is designed to bring economic opportunities to the Borders, was a good fit with Abellio's wish to widen public access to rail infrastructure - a goal it claims to have attained in its three existing English franchises, Merseyrail, Northern Rail and Greater Anglia.

Connelly said that the viability of the new Borders Railway "depends on the determination of the operator as to how it markets it. We would do that in collaboration with the tourist agencies, and with housing developers".

He added: "It would be up to the train operator to raise their game in getting people to use the railway.

"I think it's an opportunity. If we won the franchise to run it on behalf of the Scottish Government, we will do our best by it. If invited to tender, we will put in a suite of ideas about what we can do to make it work."

Transport Scotland has admitted that it expects the rebuilt 30-mile Edinburgh-Tweedbank line to take 10 years to become profitable on currently projected low annual passenger numbers, although industry observers have noted that use of new rail infrastructure has usually exceeded initial projections.

While it has admitted an underlying negative economic benefit-cost ratio, the agency has not made public the commercial and financial sections of the Borders Railway final business case, citing the need to protect the negotiating position of the Scottish ministers.

Critics of the £350 million project count the risk of undermining the smooth transfer of the ScotRail franchise alongside "farebox risk" and construction risk when calculating the controversial project's potential calls on the public purse.

Transport Scotland will next month announce a shortlist of train operators which will be invited to tender for the franchise, the award of which was recently postponed until after the independence referendum. As well as Abellio, other contenders are likely to be the incumbent, First Group, plus National Express, Hong Kong's MTR, and German-owned Aviva Trains.