THE Commons Speaker has slapped down a Tory cabinet minister who suggested she did not have to answer an MP's question because he is Scottish.

In a letter seen by The Herald, Speaker John Bercow accuses Westminster Education Secretary Nicky Morgan of "political point- scoring" over the issue.

He adds that the comments by Ms Morgan, who is also the UK equalities minister, carry "no procedural weight whatever".

The letter will re-ignite the row over David Cameron's plans to restrict Scottish MPs voting rights.

Labour MPs were outraged when Ms Morgan suggested she did not have to answer questions from Scottish politicians.

Her comments led to accusation the Tories were treating Scots as "second class" MPs just weeks after the independence referendum. In his letter, Speaker Bercow also confirmed that all MPs were "equal in the eyes of the Chair".

Glasgow North West MP John Robertson, who wrote to the Speaker to ask for clarification on the rules, said: "I am glad to have received a response confirming that Scottish Members of Parliament have an equal standing with members from every other part of the UK, and can speak on any issue in the House.

For my part, I will continue to speak out on all issues that affect my constituents in Glasgow, even if not directly."

He added that he would not be deterred by Ms Morgan's "petty" behaviour.

The row erupted after Mr Robertson asked Ms Morgan about her government's policy to allow unqualified teachers to work in some English schools.

Ms Morgan replied that the issue did not affect constituents north of the Border, adding "but I'm very happy to answer your question".

Mr Cameron was accused of betrayal when he announced plans for "English votes for English laws" (Evel) within an hour of the referendum result.