Any moves to transfer criminal justice powers to the European Union would lack democratic legitimacy, MPs have warned.

In a report published on Thursday the European scrutiny committee criticised any move to transfer substantial power from national parliaments to the European parliament.

The issue has been under consideration in the Convention on the Future of Europe, and follows controversial moves to establish a pan-European arrest warrant.

MPs are concerned at plans to extend the use of qualified majority voting for criminal justice issues.

The report said that such key areas were closely linked to the identity of states and were not an area for greater harmonisation.

"Criminal justice is a matter which identifies the state, or in the case of the UK, parts of the state," said committee chairman Jimmy Hood.

"A degree of public ownership is essential if it is to work properly. The only forum which can deliver this is the national parliament.

"Any system which allows member states to be outvoted in this area would not have democratic legitimacy. Harmonisation of criminal law and procedure should therefore proceed either by unanimity or not at all."

The committee said that harmonisation of criminal procedure should be limited to what is needed to secure mutual recognition of judgments and decisions.

And moves to adopt pan-European criminal laws should proceed only where there is unanimity, the MPs said.

The jurisdiction of the European Court of Justice should not be extended to police and law enforcement operations, or to the maintenance by member states of law and order and internal security, they added.

The committee also called for an enhanced role for national parliaments in areas such as defining the guidelines and priorities for European criminal justice policy, ensuring the principle of subsidiarity is observed, scrutinising Europol and overseeing the evaluation of EU policies in this area.