Labour's pledge to transfer devolved powers from Brussels to Holyrood after Brexit could still see some go to London instead, the Herald can reveal.

In today's manifesto, Labour will say it wants powers brought back from the European Union to go straight to the relevant region or nation.

But a Labour spokesman said that Whitehall could be given control over certain areas in “exceptional circumstances”.

The SNP accused Labour of making “empty” promises.

The admission will also reignite the furious row over what the SNP claim is an attempted power grab which threatens the Scottish Parliament.

The Conservative Government has refused to confirm that powers related to currently devolved issues, such as farming and fishing, will go to Holyrood after the UK leaves the EU.

Instead, Tory ministers have talked of the need to protect the integrity of the UK's single market, suggesting that some could be reserved to Whitehall.

Last month Labour's shadow Brexit minister Keir Starmer announced that his party would hand the powers over to Holyrood.

In a speech to the STUC, Scottish Labour leader Kezia Dugdale added: “Our starting point is that any powers returning to the UK that are already devolved should not be re-reserved.

“That means that powers over things such as agriculture, fisheries and development programmes should come straight to Holyrood, along with their budgets.”

A Labour spokesman said that the party's policy was to have a presumption of devolution.

"So that only in exceptional circumstances would the power transfer to Whitehall," he added.

"It's intended to ensure that powers don't go from Brussels to Westminster but direct from Brussels to devolved communities."

A spokesman for the SNP said: 'No-one will be fooled by this empty rhetoric."

The Conservative Government has said that Scotland will get more powers as a result of the UK's exit from the EU.

The Tories have also rejected the charge that they are trying to grab power from Holyrood.

They insist that ministers will have to take sensible decisions to protect ordinary people after the UK leaves the EU.

But SNP leader Nicola Sturgeon has said that it would be "absolutely unacceptable" if powers repatriated from the EU in devolved areas did not go to the Scottish Parliament.

"There should be no question that responsibility for agricultural policy remains with the Scottish Parliament," the First Minister said in February.

“Anything else would not be grabbing power from Europe, it would be grabbing power from (Holyrood) and that would be unacceptable.”