SHADOW Scottish secretary Lesley Laird has called on the country’s MPs to “speak with one voice” and agree a deal over Brexit and devolved powers.

However Ms Laird’s efforts were undermined by her predecessor, Ian Murray, who criticised his own party’s official line on the EU Withdrawal Bill.

The SNP also showed no appetite for compromise, with Nicola Sturgeon writing to Commons Speaker John Bercow complaining the bill is “unconstitutional” as drafted.

She asked Mr Bercow to ensure Scottish Government amendments on devolution were considered when the Bill is debated by MPs tomorrow after a stormy passage in the House of Lords.

In an unprecedented move, Holyrood withheld legislative consent for the bill last month because it would give Westminster control over powers in 24 devolved areas for up to five years.

The UK Government argues this is necessary to create UK-wide frameworks to keep regulations harmonised across the UK internal market. But the Scottish Government says this undermines the devolution settlement.

With Westminster now expected to impose the bill on Scotland against Holyrood’s will, Ms Laird advocated a compromise Labour amendment cutting the five years to three, with Holyrood’s consent only required when the UK legislates in an area involving an international obligation.

She said: “Scotland’s MPs should speak with one voice and back Labour’s bid to protect the devolution settlement “Labour has been the only party making a serious attempt to break the Brexit deadlock, and these proposals are a serious attempt to stop the UK heading towards a constitutional crisis over devolution. The people of Scotland just want this mess fixed.”

However Mr Murray attacked his own party for failing to support another amendment keeping the UK in the single market via membership of the European Economic Area (EEA).

He said: “The Government’s Brexit strategy in a complete mess, and it would be ridiculous for Labour to bail out Theresa May when so many Conservative MPs are prepared to rebel. Refusing to vote for the crossparty amendment in favour of EEA membership would be a historic mistake that would cost jobs, and we won’t be forgiven if we let the Tories get away with a hard Brexit when we have the power to stop it.”

In her letter to the Speaker, Ms Sturgeon said that if the bill passed without Holyrood’s consent it would create “an unprecedented constitutional position, which puts at risk 19 years of constitutional convention and practice, on which devolution relies”.

Scottish LibDems’ leader Willie Rennie said: “This is an issue of immense national importance and all of the amendments submitted deserve to be heard and scrutinised.

“Nicola Sturgeon must now do the right thing and instruct her MPs to back Amendment 19 calling for a people’s vote on the final deal and the chance to exit from Brexit.”