This is part of a bid to alleviate the costs of staging the event.

In a statement, the Canton of Valais said the International Olympic Committee (IOC) had given their backing to other local authorities being able to co-sign the Host City Contract, usually done by the city which has been selected to host the Games in conjunction with the respective National Olympic Committee.

"They have obtained an agreement in principle from the IOC concerning the conditions of their engagement and the clarification of responsibilities," the statement read.

The move, which marks a significant step in Sion formalising a bid, will allow costs for the Winter Olympic Games to spread throughout the Valais region and ensure the city itself is not left with a considerable financial burden.

Sion's bid includes holding events across Valais, as well as in other Cantons such as Bern, Freiburg and Obwalden.

"The public authorities will guarantee the aspects that fall within their remit, such as public security and the sustainable infrastructures located on their territory," the Canton of Valais statement added.

The IOC said the candidature process for the 2026 Winter Olympics, designed to reduce the costs for bidding cities, had allowed the organisation to "adopt a more flexible approach regarding the split of financial responsibilities between the relevant actors in the host country".

"The Olympic Winter Games 2018 were an example," the IOC added in a statement sent to insidethegames. 

"Pyeongchang is a small city and did not have the financial capacity to sign the Host City Contract alone, so the region was also a signatory."

The announcement comes with barely a month to go until a crucial referendum on June 10 in Valais, which will decide whether to press ahead with the attempt.

A "no" result in the referendum should definitely mean the end of the bid, while a "yes" result will trigger an extra CHF100 million (£65 million/$99 million/€83 million) of funding. 

It is possible, though, that a further nationwide referendum may be required next year after a motion for one was approved by the Swiss Parliament.

Swiss bid supporters have worked hard on a public consultation and meeting campaign in a drive to inform residents and gain support.

A new poll has suggested support for Sion's candidacy is rising and is now neck-and-neck with opponents of the bid.

Switzerland has not hosted the Winter Olympics since St Moritz in 1948.

Sion has bid three times for the Games, losing to Denver for 1976, Salt Lake City for 2002 and Turin for 2006.

Graz in Austria, Sapporo in Japan and Stockholm in Sweden are among the other contenders for the 2026 Winter Olympics.

Erzurum in Turkey have announced plans to bid while Calgary in Canada is also likely to hold a public ballot between October and January.

There may also be a joint Italian bid from Milan, Turin and Cortina d'Ampezzo.

A 2026 host city is due to be chosen by the IOC in 2019.