Emmanuel Macron is leading demands for the UK to be forced to commit to mirroring EU rules on employment and the environment forever if it wants a post-Brexit free trade deal with the bloc.

The French president has reportedly instructed the European Commission to tell Britain that the price of a deal will be a cast iron guarantee from Downing Street that when the EU upgrades its rules the UK will follow suit.

One diplomat told The Telegraph that 'France wants dynamic alignment across the board' while another said 'full dynamic alignment makes sense' as an 'opening bid' in trade talks.

The French demands echo those of an influential group of MEPs - the European Parliament's EU-UK coordinating group - which is also asking for 'dynamic alignment'.

A leaked document from the group calls for the UK to update regulations and red tape as and when the EU does in a handful of areas including workers' rights, environmental protections and state aid.

Emmanuel Macron, pictured in Paris on Wednesday, is reportedly demanding the UK agree to mirror EU rules forever if it wants a post-Brexit trade deal

The MEPs said that without a commitment to a 'level playing field', upheld by 'robust commitments', there could be no zero tariff, zero quotas trade agreement.

MEPs do not have a formal say in the negotiating process but they will have to vote on any final agreement which means EU negotiators will have to listen to their concerns.

The MEPs' negotiating suggestions will reportedly be voted on in the European Parliament next Wednesday.

The demands made by Mr Macron and the similar ones made in the MEPs' resolution which was leaked to the Guardian will spark Brexiteer fury and will be dismissed by Number 10.

They represent an even tougher stance than the one already adopted by the EU's chief Brexit negotiator Michel Barnier.

Mr Barnier has sought alignment on rules and regulations in core areas with formal trade talks between the two sides due to start in March.

Many in the bloc are adamant the UK must agree to sticking to the same standards as the EU in order to stop Britain 'undercutting' the rest of Europe.

They fear that a divergent UK would be able to become a more attractive destination for business than the bloc.

There are also concerns that the Brexit trade deal must be future-proofed so that the the UK cannot simply ditch regulations in the decades to come.

Brussels officials believe a legally binding commitment to mirroring future EU rules would protect against a more competitive UK emerging on the bloc's doorstep.

One diplomat told the Guardian: 'We are not going to agree that quota-free, tariff-free access, if there is no level playing field.'

Alignment on rules will be a crunch issue during post-Brexit trade talks between the EU and the UK.

Brexiteers believe the UK must be free to do what it wants on rules and regulations after the Brexit transition period ends in December this year.

Boris Johnson said at a speech on Monday this week there would not be 'alignment of any kind' between the UK and the EU after Brexit

Boris Johnson has adopted a hardline position on the issue, using a big speech on Monday to proclaim there would not be 'alignment of any kind' between the two sides.

He said he wanted Britain to be an 'an independent actor and catalyst for free trade across the world'.

The EU has made clear that the level of alignment the UK is willing to subscribe to will directly affect the generosity of any deal offered by Brussels.

A failure to accept any alignment would therefore likely result in a more distant and less beneficial future trading relationship.