Decision-making in the eurozone must be strengthened and not “paralyzed”, European Parliament president Martin Schulz has warned over UK demands for what could effectively amount to a veto on eurozone issues.

In his address at the start of a heads of government meeting, Mr Schulz raised several concerns about the special arrangement the UK is seeking as it tries to redefine its relationship with the EU.

One of the UK’s demands is for a recognition that the EU is  “a multi currency union”.

Mr Schulz insisted the Treaties were very clear that the currency of the EU was the euro and the UK was guaranteed an opt-out.

“Opening up this chapter without an unequivocally good cause risks introducing ambiguities and could be detrimental to the functioning of the Economic and Monetary Union… We must avoid creating a de facto veto right for any member state in the European Council on eurozone issues,” he said.

British Prime Minister David Cameron has gone on record saying the goal is not to obtain a veto for the UK but Mr Schulz insisted the text on the table risked creating this possibility.

“It matters little if there is no explicit wish for a veto. The danger is clearly there and is too important to neglect.”

This was one of the concerns the European Parliament had, he said, adding any safeguard mechanism to control benefit abuse must not discriminate between EU citizens.

Mr Schulz said any rule changes to solve practical problems created by freedom of movement will have to be approved by the European Parliament. “No parliament in the world can prejudge the outcome of its legislative work,” he said, making it clear that the UK could not be given a guarantee on whether and how its demands to curb benefits for EU migrants would be met.

Mr Schulz’s comments broadly outline the difficulties Mr Cameron faces to get a deal, which he hopes will help sway a sceptical British public when they vote in an in-out referendum that could possibly be held in June.