THOUSANDS of Orange Order members and supporters from Northern Ireland will travel to Edinburgh next weekend to stand alongside their "Scottish brethren" at a controversial march in support of the Union, it has emerged.

Rev Mervyn Gibson, the assistant grand master of the Grand Orange Lodge of Ireland, told the Sunday Herald he and up to 2000 other Unionists from grand, county and district lodges would make the trip for next Saturday's event.

"Scottish brethren stood beside us during the Troubles and we need to stand by them when their place in the union is under threat politically," he said this week.

The Grand Orange Lodge of Scotland, which is organising the rally, expects some 10,000 band members and marchers to attend what will be the biggest referendum gathering of the year.

The Orange Order is an official No campaigner in the referendum with its own pro-Union campaign group, British Together, and described itself as "fervently opposed" to independence.

Better Together insists the Protestant movement will "never" be part of its operation. Some in Better Together fear Saturday's march could backfire, especially among Catholic voters usually loyal to Labour, and boost Yes.

Gibson, who was recently criticised for telling a public meeting that it was sad a new mural dedicated to Sinn Fein leader Gerry Adams was "not a memorial mural," said the referendum was being closely followed by Orange members in Ulster. He said: "We had the country grand master of Glasgow, Eddie Hyde, speak at the Belfast 12th [of July parade] so that we could hear about the referendum."

Asked if the Order's presence might inadvertently shift people to vote Yes, he said: "If this march gets people to vote Yes the rationale is very shallow. It could bring out people to vote when they see an expression of Britishness. It could have a positive effect."

The mix of religion and politics before the referendum has raised fears the September 13 march could be a flashpoint for trouble. At the Orange walk in Glasgow in July, a girl was struck in the face by a bottle and there were 18 arrests for drunkenness and disorder.

East Renfrewshire Labour MP Jim Murphy said the violence was a "scar on Glasgow", and said this weekend's march "shouldn't go ahead".

Asked if Saturday's march might be a flashpoint, Gibson said: "The Order will be doing everything to ensure there will be no incidents. I don't think we are bringing religion into it [the referendum]. The Orange Order stands for the United Kingdom of all religions."

The march is due to start from the Meadows at 11am and ends at the Scottish Government HQ at St Andrew's House. Police Scotland has asked City of Edinburgh Council to impose a series of strict licensing conditions, including "no militaristic uniforms", a ban on placards, flags and posters "bearing inflammatory images or words", and no playing of musical instruments outside a church service.

Robert McLean, executive officer of the Grand Orange Lodge in Scotland, said: "The numbers are looking just over 10,000, from Scotland, Northern Ireland and a few coming up from England."

A Better Together spokesman said: "This organisation is not part of our campaign."