An Irish flag and a poster of Taoiseach Leo Varadkar were set ablaze after being erected on a boat placed on top of a loyalist bonfire.
The pyre in Moygashel, Co Tyrone previously made headlines when the boat was placed on it.
By Saturday evening, a banner reading “Good Friday Agreement? That ship has sailed” had been added to the side of the boat, and a mock copy of the 1998 accord with the words “null and void” printed over it.
The bonfire, titled “No Irish Sea Border Bonfire”, was lit around 11pm following a parade and an address by loyalist activist Jamie Bryson.
It also features a banner reading “Moygashel says ‘No’ to Irish Sea border”, referring to the unionist and loyalist communities’ opposition to post-Brexit trading arrangements.
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Most of the bonfires to mark the North's traditional July 12 celebrations will be lit on July 11.
There has been controversy in previous years, with politicians’ election posters and Irish flags placed on the pyres.
Earlier on Saturday, the only annual Orange parade in the Republic of Ireland took place.
Orange lodges from counties Donegal, Monaghan and Cavan – along with guests from the North – took part in the seaside procession in Rossnowlagh.
Meanwhile Sunday will see the annual Drumcree parade leave Carleton Street Orange Hall in Portadown, Co Armagh, to a church service at Drumcree Parish Church.
This year marks the 25th anniversary of the parade being prevented from completing its traditional return route along Garvaghy Road.
The Parades Commission again this year refused permission for the return leg of the parade.
The stand-off at Drumcree hit the headlines in the 1990s with nationalist residents of the Garvaghy Road resolutely opposed to the parade passing through the area.
It led to violent clashes for several summers and political tensions necessitating a major security operation.
Most of the bonfires are set to be lit on July 11, on the eve of the marking of the victory of the Protestant King William over the Catholic King James II in the Battle of the Boyne in 1690.
That victory secured a Protestant line of succession for the British crown.
Most of the hundreds of bonfires constructed in loyalist neighbourhoods across the North pass off without incident, but several continue to be the source of controversy.
In previous years, there have been complaints from nationalist and cross-community politicians about their images being placed on the fires.
It is the busiest date for the NI Fire and Rescue Service which usually deals with hundreds of calls related to the towering pyres.
