Campaign group Republic has called for a parliamentary inquiry into the Queen's "underhand, deliberate and provocative" interventions into the Scottish independence referendum.

The group has agreed with BBC analysis that comments made by the Queen have been a deliberate intervention in the debate. This is in direct breach of the constitutional duty of a monarch to stay away from political debates.

The group will be writing to the Commons political and constitutional reform committee as well as the Justice Secretary, calling for an inquiry into the actions of the Queen and her advisors.

Republic's chief executive Graham Smith said tonight:

"The monarchy and the Queen have been around long enough to know what they're doing. Comments made by the Queen last weekend and widely reported in the press as pro-Union were a deliberate attempt to influence the vote."

"Earlier briefings to the press about the Queen's concern were also clearly a deliberate attempt to influence the result of today's referendum."

"We would normally expect a head of state to take an active interest in such a momentous referendum, but the deal with the monarchy is that the monarch stays quiet and keeps out of these debates."

"The real problem is the system. But that doesn't excuse the Queen making her views known in such an underhand way while having her press office insist she is impartial."

"We're calling on MPs to investigate the role of the Queen in this referendum campaign and the convention of royal impartiality. Of course the Queen is damned if she does and damned if she doesn't - but the bottom line is that the rules are there and the Queen can't pick and choose when to follow them."

"It's perfectly understandable to expect a head of state to speak out in defence of their state. The Queen however wants it both ways - her priority is clearly to intervene on the side of the No campaign while protecting her own position through these dishonest tactics."

"These comments and reports have been a deliberate and provocative intervention in a tightly contested referendum - but the Queen hasn't the nerve to come out openly and so resorts to these duplicitous tactics."

"Republic takes no position on whether Scotland should be independent, but it's unacceptable for the Queen to be interfering in this way while still asserting her neutrality."