THE First Ministers of Scotland and Wales have written to peers setting their own proposed changes to crucial Brexit legislation.

The Scottish and Welsh governments have been locked in a dispute with the UK Government over the return of devolved powers from Brussels once Britain leaves the EU.

READ: Nicola Sturgeon and Carwyn Jones's full message to Lords

While UK ministers have brought forward amendments to the EU (Withdrawal) Bill aimed at addressing the disagreement, Nicola Sturgeon and Carwyn Jones said they did not have their support.

The leaders have written to the House of Lords ahead of its consideration of aspects of the Bill related to devolution on Monday.

UK ministers want to retain temporary control in areas such as agriculture, fisheries, food labelling and public procurement after Brexit.

READ MORE: ‘Ulster is a powder keg which Brexit may ignite’

They say a “temporary restriction” on the devolved governments using some of the powers returning from the EU is “to help ensure an orderly departure from EU law” and allow common frameworks to be established.

In their letter, the First Ministers said their governments agreed common frameworks are appropriate in some cases, however they said UK ministers’ amendments would see them only “merely consulted” on these.

They have called for further amendments to ensure that the temporary restriction on devolved powers would require their consent and any primary legislation required to establish common frameworks must be agreed by them.

They have also called for a “sunset clause” on the restrictions, limiting how long they would be in effect without further action.

While talks between the devolved administrations and the UK Government continue, the leaders stated that they “would be pleased to put forward detailed amendments if it proves impossible to reach agreement”.

“The two governments have also asked that the UK Government agree a level playing field and make a commitment not to bring forward legislation in respect of England in those areas where it is agreed common frameworks are to be established,” they added.

The letter to the Lords follows a meeting between the First Ministers and Theresa May earlier this week.

Speaking afterwards, Sturgeon said the “issues that remain between us are not insignificant but neither are they insurmountable”, while Jones said he was “hopeful” of an agreement.

Meanwhile, it was revealed the UK could decide not to impose border checks after Brexit if it fails to reach a customs agreement with the European Union, under plans reportedly being considered in Whitehall.

Amid concerns about tailbacks and hold-ups at major ports – and the thorny issue of the Northern Irish border – officials are reported to have discussed the option of not applying checks to enable trade to flow smoothly.

The Government said it had set out its aim for a deal with Brussels which would make trade “as frictionless as possible”, but added “we have a duty to plan for the alternative”.

Border operators are said to have been involved in talks with officials – covered by a non-disclosure agreement to maintain confidentiality – about the arrangements which could apply after Brexit. If there was no deal with the EU “this is what we call the ‘throw open the borders option’”, said one operator.

Under that scenario the UK would unilaterally decide not to enforce customs and other border checks – assuming that the EU would follow suit – temporarily maintaining frictionless trade.

Transport Secretary Chris Grayling has said separately there would be no checks on lorries arriving at Dover, and suggested that trade would flow seamlessly after Brexit.

“We will maintain a free-flowing border at Dover, we will not impose checks in the port,” he said on BBC’s Question Time.

Labour MP Chuka Umunna said: “If it becomes a ‘third country’ outside the EU’s Customs Union, the UK will almost certainly be under legal obligations to mount customs checks at its border.”