According to reports in the Swiss media, right wing parties such as the Swiss People's Party are opposed to the plans to cooperate more closely with Brussels on security and other matters, and are likely to attempt to force a referendum on the treaties.

Speaking to Swissinfo, Foreign Minister, Micheline Calmy-Rey confirmed that:

"We are very conscious of this problem. The referendum is a weapon - or perhaps I should rephrase that and say an instrument - in the hands of the Swiss people who want to achieve certain objectives."

She went on to add that:

"I always have to explain the Swiss referendum process to my EU colleagues and I have to tell them that there is nothing I can do about it. But I will do my utmost to ensure that the cabinet pushes for the right result, and I am sure that we will succeed."

However, the Foreign Minister admitted that if a compulsory referendum is forced, the government's chances of achieving the desired results are slim, as it would need to secure a majority of the popular vote, in addition to the backing of 13 of Switzerland's 26 cantons.

"I am not in favour of such a referendum because we would need a double majority and this would certainly not work to our advantage," she told Swissinfo.