The Scottish Parliament should not have a veto over the UK triggering Article 50, the Supreme Court has heard.

Lord Keen, the UK Government's advocate general, made the argument in the second day of the hearing in London.

The devolved administration believes Holyrood should have to pass a legislative consent motion before Article 50 can be triggered.

They believe Brexit will result in a change in the Scottish Parliament's legislative competence.

The First Minister has said: "The Scottish Government is clear that triggering Article 50 will directly affect devolved interests and rights in Scotland."

She added: "So legislation should be required at Westminster and the consent of the Scottish Parliament should be sought before Article 50 is triggered."

Lord advocate James Wolffe will put the Scottish Government's argument forward on Wednesday.

Lord Keen reminded the 11 Supreme Court justices that the Scotland Act 1998, the legislation which created the devolved parliament, stated "international relations, including relations with territories outside the United Kingdom, the European Union (and their institutions) and other international organisation... are reserved matters" which remain at Westminster.

The advocate general told the court the Scotland Act makes it "perfectly clear" the country's "relationship with the European Union" is not part of Holyrood's powers.

Therefore, Lord Keen argued, the Scottish, Welsh and Northern Irish administrations could not "qualify or abrogate" Downing Street's right to trigger Article 50.

He said: "I would submit these reservations are fatal to reliance on devolution legislation as giving rise to any necessary implication, or indeed any other indication, that the government cannot exercise its foreign affairs and treaty prerogative in the ordinary way."

The advocate general added the Sewel convention, a name given to the legislative consent motion which MSPs use to give their approval to changes made to Holyrood's devolved matters by the UK Government, was political in nature as opposed to statutory.

Lord Keen argued the Scotland Act 2016, which mentions the Sewel convention, did not make it statutory.

Judge Lord Sumpton disagreed with Lord Keen on his point. Lord Sumpton told the advocate general "it cannot be described as a purely political force once it is enacted in a statute".

"It was made perfectly clear during the package of the Scotland Act 2016," the advocate general replied.

"That the intention was simply to incorporate in statutory form the existing convention and no more than that."

In his closing remarks on Scotland, Lord Keen rubbished the Scottish Government's case saying it had "no substance".

The advocate general told the court: "The conclusion of the Article 50 case advanced by the lord advocate is that there is by virtue of the Sewel convention a constitutional requirement using the terms of Article 50 that must apply before the United Kingdom and takes steps in terms of Article 50 to leave the EU.

"However, the lord advocate makes no effort in his case to explain how a convention which provides in terms that it does not apply as a rule in all circumstances, could even be a requirement, let alone a constitutional requirement and therefore there is doubt as to where that case actually goes.

"In my respectful submission, there is no substance in the case that is being advanced there by the lord advocate."

A verdict is expected to be reached by the court in January.