ALEX Salmond has said the Queen and the royal family must stay out of the debate about Scottish independence.

The former First Minister’s comments were in response to a meeting between Prince William and Gordon Brown last week and reports of the royals being deployed in a "charm offensive" to save the Union. 

The meeting in Edinburgh on the last day of the Earl of Strathearn's week-long visit to Scotland prompted an outcry as it came just weeks after Brown launched a new campaign to stop independence.

Brown was seen attending the Palace of Holyroodhouse by Channel 4. However, the broadcaster was asked not to show the images of the former prime minister in the grounds of the palace on privacy grounds.

READ MORE: Prince William and Kate hold secret talks with Gordon Brown on independence

Now Salmond, who leads the pro-independence Alba Party, said that it would be a fatal error for the monarchy to allow the perception that they were taking sides in the constitutional debate.

In a message to supporters, he said that it was also essential to “strike while the iron is hot” in progressing the case for independence while the “pro-Union” side of the debate is in “disarray”. 

"Whatever Prince William thought he was doing by agreeing to a confab with Gordon Brown just as he set up his latest campaign for the Union ... we should have no hesitation in seeing from that meeting, Unionist preparation for attempting to persuade a constitutional monarchy to intervene in a constitutional debate which should be left to the people," said Salmond.

"It would be very wise for the royal family to follow what has been the Queen’s example over her long reign, to keep the monarchy over and above politics, and it would be foolish to have a situation in which it can be said that the monarchy is involved in the Scottish Constitutional debate."

READ MORE: Scottish independence: 'Queen to head charm offensive to save Union'

Salmond added: “Back in 2014 David Cameron made a last-ditch desperate and failed attempt to drag the Queen into politics. The Brown meeting shows poor judgement on both sides but the same degree of unscrupulous unionist desperation. The independence team should take note."

Soon after the Holyrood election, Brown announced his Our Scottish Future think tank which will become a “campaigning movement” seeking to appeal to “middle Scotland”, those who are not entrenched in their positions on the Union or independence.

The former prime minister, who played a key role in the No campaign during the 2014 vote, has said those in middle Scotland are “patriots not nationalists” who want to see greater cooperation between the UK’s governments.

Ahead of the Scottish independence referendum in 2014 the Queen reportedly said she hoped voters would “think very carefully about the future”.

Before the Queen’s reported comment Buckingham Palace had issued a statement, following speculation she was growing increasingly concerned about Scottish independence, saying any suggestion the monarch would wish to influence the outcome of the referendum was “categorically wrong”.

Salmond’s intervention today was made in a press statement which said that his party's membership continues to rise after the Scottish Parliament election. 

Alba failed to win any seats in the Holyrood election on May 6 leaving Salmond and his supporters disappointed.

At the weekend, Salmond launched Alba International, a global membership section of the party, and he believes the party’s membership will continue to grow as it presses for greater urgency in progressing the independence case. 

The former SNP leader added: "It is quite clear that the forces of the union, David Cameron previously, and now Gordon Brown, have no compunction in getting themselves ready and set for what is coming in the next referendum campaign. However, the Scottish Parliament elections have left them in a state of disarray. 

"That is why the case for Scottish independence must be progressed now as a matter of urgency. The Tories at Westminster are surprised that they are not already facing a renewed constitutional challenge and are wondering what on earth is going on. 

"It would be infinitely better for the independence side to seize the moment and strike when the iron is hot to progress the constitutional issue. Alba membership continues to rise as we press for the case for Scottish independence to be progressed with urgency and democratic determination." 

Salmond also updated supporters that the party’s conference may be brought forward to a date earlier in September due to rising delegate demand requiring a larger venue for the event. 

He also provided an update of four interim appointments of Cllrs Chris McEleny, Lynne Anderson and Caroline McAllister and former MP Corri Wilson approved by the party’s 32 candidates who stood in the Scottish Parliament elections.

They will assist in the party’s development until the establishment of the first National Executive elected at Alba inaugural conference. 

Salmond said: "Alba is strong and growing. These appointments will consolidate that progress through to the inaugural Conference in September when the members will elect their Executive and office bearers. I am grateful to Chris, Lynne, Caroline and Corrie for agreeing to take forward these important tasks."

Commenting interim General Secretary Chris McEleny said; "Alba is Scotland’s newest and fastest growing political party. Our membership numbers are rising week on week since the Scots Parliament elections.

"Alba can make a valuable contribution to the independence case, particularly in ensuring it is put forward with immediacy, strength and determination. We are all excited about the prospect of building a new party which will abide by our aspiration of living in the early days of a better nation.”

A spokeswoman for Kensington Palace referred The National to a statement made last week.

It said: “During his time in Scotland, Prince William has spoken to a broad range of people from different communities including politicians from across the political spectrum.”

The Duke also held a private meeting with Nicola Sturgeon last week.

A spokeswoman for Buckingham Palace declined to comment.