Published Tuesday, 01 April 2014
The Order has demanded a meeting with US officials in Belfast. (© Getty)
The Order said the Historical Enquiries Team, in a response to its request for information, has said that of the 266 weapons used in the killings of Orangemen, 149 could be traced back to the America.
The Grand Orange Lodge of Ireland said it believes that American weapons were used in the killing of Orangemen at Tullyvallen Orange Hall in Co Armagh in September 1975.
The Order believes that most of the weaponry "probably arrived via republican sympathisers in the United States".
While others may have come from thefts at military installations, the Order said.
Grand Secretary Drew Nelson said he is now seeking a meeting with the American Consulate in Northern Ireland to discuss the "alarming revelations".
An Orange spokesman added: "This is a very serious matter and the United States owes it to the families of those murdered to investigate how a majority of the weapons used in the commission of murder of our members appear to have been from the USA."
In a statement, the US Consulate in Belfast said: "The US Consulate would be pleased to meet with representatives of the Orange Order to hear their concerns first-hand.
"We look forward to discussing with the Orange Order the broad range of issues facing the people of Northern Ireland, including ways to further advance peace and community relations.
"It would be inappropriate for us to make any public comment in advance of these discussions."
© UTV News