Scottish independence could put UK security at risk as its enemies could exploit the "uncertainty or distraction" caused by the break-up of Britain, according to the Foreign and Commonwealth Office (FCO).
Scots abroad could also be put at greater risk of "child abduction, forced marriage or crime" through the loss of the UK's consular assistance, the FCO suggested.
It has urged the Scottish Government to provide evidence for its "claims about the status of an independent Scotland, including its membership of international bodies" such as the European Union, the United Nations, Nato, the World Bank and the International Monetary Fund.
The FCO claims to offer "clarity and fact" on the independence process in a submission to the Commons Foreign Affairs Committee released on Wednesday.
Alex Salmond and the SNP are pushing for a referendum by 2014
It insists that independence would create "a UK land border" and "harm the Scottish economy" by withdrawing Scotland from the UK's 14,000 treaties and global network of foreign investors.
The FCO said it has not been provided with any evidence to support the Scottish Government's "assertion" that Scotland "would continue to be a member of the EU in the event of independence, and would not have to negotiate the terms of its membership as a new member state".
It is unclear whether the Scottish Government possesses any legal evidence to support its EU claim as it has taken the Scottish Information Commissioner to court to prevent the public knowing if it exists.
The FCO said Scotland would have a diminished influence in EU negotiations, particularly under the new proportional voting system being introduced in 2014.
It would "not be a permanent member of the United Nations Security Council" and "would also not belong to, or be invited to join, the other main international groupings of the most influential and economically significant countries, such as the G8 or G20".
The SNP is due to vote on overturning its historic opposition to Nato at its party conference on Friday, but the FCO warns that, even if its members vote to take Scotland into Nato, its entry is not guaranteed.
Commenting on the FCO's security concerns, an SNP spokesman said: "When ex-home secretary John Reid made similar claims in 2006, he was ridiculed by a genuine expert, the late Professor Paul Wilkinson.
"Independence will mean that we continue to work in co-operation with other parts of the UK, our European neighbours and international partners on common defence and security interests."
Meanwhile, the Ministry of Defence has also given evidence to a second House of Commons committee which is examining the defence implications of an independent Scotland.
On the eve of the SNP conference, the MoD suggested that SNP defence spokesman Angus Robertson's resolution to keep Scotland in Nato on the condition that it will be allowed to remove nuclear weapons may have an impact on its Nato membership bid.
Salmond met with David Cameron to agree on a referendum
"There is no guarantee that Nato membership would be automatic," the MoD told the Commons Defence Committee in written evidence published on Wednesday.
"If an independent Scotland decided that it wanted to be a member of Nato, the North Atlantic Council would need to decide whether or not it would meet the criteria for membership.
"Nato's strategic concept, as agreed by all allies at the 2010 Lisbon Summit, reiterated that Nato's deterrence posture will consist of both nuclear and conventional forces and that Nato will remain a nuclear alliance for as long as nuclear weapons exist.
"The Scottish Government's position regarding nuclear weapons and their presence in its territory would therefore be an important consideration."
The MoD warns that relocating the UK nukes would come with a "huge cost", probably exceeding the £3.5 billion it cost to upgrade Faslane for the introduction of Trident.