The UK is set to join nine European Union (EU) states in signing up for a new, joint European rapid response military intervention force.

The so-called “letter of intent” will help formalise the plan, led by French President Emmanuel Macron, which is widely perceived as another step towards the creation of an EU army.

Defence ministers from Germany, France, Belgium, Denmark, the Netherlands, Estonia, Spain, Portugal, and the United Kingdom are expected to sign the document in Luxembourg on Monday.

The initiative is separate from PESCO, the Brussels defence cooperation agreement, signed in November 2017 by 23 member states, meaning it is open for Britain to join after Brexit.

“This is clearly an initiative that allows the association of some non-EU states,” French defence minister Florence Parly told the newspaper Le Figaro. “The UK has been very keen because it wants to maintain cooperation with Europe beyond bilateral ties.”

President Macron laid out his vision for an independent European defence force and policy in a staunchly europhile speech last September.

The demands were perceived as a challenge to NATO, where officials are concerned about the EU duplicating the purpose of the defence pact, and isolating itself from the U.S.

The initiative involves “joint planning work on crisis scenarios that could potentially threaten European security”, a source close to Mrs Parly added.

The “scenarios” reportedly including natural disasters, intervention in a crisis, and the evacuation of nationals.

Since 2007, the EU has had four multinational military “battlegroups” at its disposal, but troops have never been deployed due to political disagreements.

President Macron hopes that by focusing a smaller number of nations, the force will be more easy to control and deploy, free from politics of so many member states, AFP reports.

Italy had initially been interested in the initiative, and the new populist government “is considering the possibility of joining” but has not made a final decision, Mrs Parly said.