A Conservative policy group commissioned by Mr Cameron to look into national and international security is publishing its report, which argues that defending Britain should be "of paramount importance" to a future Tory Government.

The report calls for the creation of a US-style National Security Council to form long-term strategies on foreign policy, defence, internal security and national cohesion.

And it recommends a much higher priority for homeland defence, with the establishment of a dedicated civil emergencies force with a permanent command headquarters to provide leadership in the event of a terrorist attack or other major disaster.

The report will be launched by group chair Dame Pauline Neville-Jones. While Mr Cameron will attend the launch event in London, he is not committed to adopting the group's recommendations as Tory policy.

The report accuses the Government of damaging Britain's international reputation and the effectiveness of the trans-Atlantic alliance by "naively underestimating the challenge of state-building in hostile environments".

It says that the Government has undermined security at home by treating people from ethnic minority backgrounds as members of groups rather than individual citizens.

And it states that, under Labour, the Government has overstretched the armed forces, leaving them without sufficient reserves.

Among its recommendations are the creation of a new Partnership for Open Societies, bringing together leading democracies and regional powers to promote stable, liberal democracy in the broader Middle East.

The report also calls for a four-yearly defence review to ensure that armed forces capabilities match up to the missions they are required to undertake.