The outcome of the Scottish independence referendum could still end up in the courts even though Holyrood has been given the legal power to stage the poll, a Lords Committee has warned.
The legal instrument that has paved the way for the referendum, known as a Section 30 Order, could itself be deemed illegal, according to the House of Lords Constitution Committee.
SNP proposals to extend the franchise to 16 and 17-year-olds could also breach data protection laws as it could lead to the publication of the names and addresses of minors, it stated.
The committee said a legal challenge to the referendum result would be unlikely to succeed. But it added: "We cannot rule out the possibility that such a claim or petition might nonetheless be brought, with all the consequences of the potential for delay and disruption and for bringing the courts into the heart of the process that such an action may have."
It states that a challenge may be brought on the grounds that statutory powers must "promote and not frustrate" the objectives of the Act in question.
The committee warned that some may argue that by facilitating the referendum through Section 30 of the Scotland Act, the Government may frustrate the objectives of the Act - which is to facilitate devolution and not independence.
"It might then be argued that it is an improper use of a devolution statute, such as the Scotland Act 1998, to arrange for a referendum on the different and separate issue of independence," it stated. "It cannot safely be said that the arrangements proposed put the matter beyond all legal challenge."
The Section 30 Order was signed without the scrutiny of the UK or Scottish parliaments, breaching the Prime Minister's earlier insistence that "the future of Scotland must not be worked out in secret behind closed doors", the committee complained.
Committee chairman Baroness Jay of Paddington said: "We are concerned that there are still many potential pitfalls ahead. Proceeding via a ministerial order makes the opportunity to the UK Parliament to contribute to the process almost negligible."
She added: "In order for this referendum to be timely, robust and secure, further work is necessary to ensure that these issues are resolved."