Suspected criminals could be able to escape justice more easily after independence by crossing the border into England, a report is expected to suggest today.

Home Secretary Theresa May will launch the latest Whitehall analysis of the potential consequences of Scottish independence in Edinburgh.

The paper will concentrate on the implications for security and is expected to warn independence would make it more difficult to arrest a suspected offender who had fled to another part of the UK.

"The European Arrest warrant is not the same as the right of arrest within the same country", a Downing Street source said.

The report is also expected to warn the UK could be prevented from sharing intelligence obtained from other countries with an independent Scotland.

At the weekend a St Andrews University academic warned that Scotland's national security could be jeopardised by leaving the UK.

Professor Richard English, director of the Centre For The Study Of Terrorism And Political Violence, said that if there was a Yes vote crucial relationships between the security services and police forces north and south of the border would have to be "established anew".

The SNP has called on Mrs May to use her visit to distance herself from "scaremongering claims" by Prime Minister David Cameron that an independent Scotland would be at greater risk of terrorist.

MSP Sandra White, who sits on the Scottish Parliament Justice Committee, said: "This is a key test for the Westminster Government and the scaremongering approach to the referendum that has served them so poorly."