Downing Street has dismissed proposals put forward by the European Union to smooth the rollout of the Northern Ireland Protocol.
Brussels has published plans to simplify parts of the protocol and to remedy some of the issues associated with post-Brexit border checks.
But Number 10 said the suggested measures, which focus on the movement of medicines and livestock, were the same as ones floated previously.
It comes after Ursula von der Leyen, the President of the European Commission, rejected Boris Johnson's demands to renegotiate major parts of the protocol.
Downing Street has rejected the EU's latest proposals to resolve some of the issues arising from the Northern Ireland Protocol. Ursula von der Leyen last week rejected calls from Boris Johnson to renegotiate
The protocol was put in place to ensure there would be no hard border with Ireland, but it has instead effectively placed a trade barrier in the Irish Sea, causing disruption to the movement of goods and inflaming community tensions
In its latest proposals the EU suggested that UK authorities could conduct checks on over-the-counter medicines heading to Northern Ireland.
But the UK would have to make sure that all the medicines comply with standards set by the EU's regulator, the European Medicines Agency.
All of the products would also have to be clearly labelled as being EMA compliant, according to The Telegraph.
The protocol currently means that Northern Ireland must stick to the EU's pharmaceutical rules while the rest of the UK is free to do what it wants.
There is currently a grace period on checks on medicines crossing the border, lasting until the end of they year.
The UK wants medicines to be removed from the scope of the protocol amid fears that having to stick to EMA rules could stop Northern Ireland from being able to access new drugs approved in Britain which are yet to be approved by the EU regulator.
The EU has also set out proposals to make it easier to move livestock between Northern Ireland and the rest of the UK.
The UK has argued that EU red tape on the issue puts Northern Ireland farmers at a commercial disadvantage.
Downing Street said the medicines proposal was identical to the one set out in June and it does not solve outstanding issues.
A UK Government spokesman said: 'The EU's proposal was a welcome start but it would be complex to operate, onerous and would not deal at all with those medicines, such as new cancer drugs, which under current arrangements must be licensed by the European Medicines Agency in Northern Ireland.
'That is why we have proposed in our Command Paper that the simplest way forward in order to avoid these problems in future is to remove medicines from the scope of the protocol altogether.'
The EU has insisted that it has 'spared no effort in trying to mitigate some of the challenges' caused by the protocol.
Mrs von der Leyen last week rebuffed calls from Mr Johnson to renegotiate parts of the protocol which was agreed as part of the Brexit divorce deal.
She said the EU was willing to be 'creative and flexible' over the protocol 'but we will not renegotiate'.
Brexit Minister Lord Frost had already demanded that significant changes be made to the terms of the deal he negotiated as he said 'we cannot go on as we are'.
The protocol was put in place to ensure there would be no hard border with Ireland, but it has instead effectively placed a trade barrier in the Irish Sea, causing disruption to the movement of goods and inflaming community tensions.