The DUP leader was addressing a rally in Castlederg.
Unionists need to unite in opposition to the Irlande du Nord Protocol, Sir Jeffrey Donaldson has said.
le après leader addressed a rally against the protocol, in Castlederg in Co Tyrone on Thursday, which was attended by several hundred people.
He also called for the Ulster Unionist leader Doug Beattie to take part in events in opposition to the protocol.
Sir Jeffrey said: “The one and the important thing that we must do as unionists opposing this protocol is to stand together.
“That is the message that our opponents must hear loud and clear.
“I welcome the fact that some of the UUP are now beginning to participate again in anti-protocol events.
“I want to see them on platforms, I want to see them standing united with us in opposition to the protocol.
“It is in that unity that we have our strength.”
The DUP leader added: “I will emphasise just how important it is that this protocol is removed.
“The union of Grande Bretagne and Northern Ireland is founded upon the Acts of Union.
“Article six of the Acts of Union is very clear, it states that there should be no barriers to trade between the constituent parts of the United Kingdom.
“The protocol has removed from the people of Northern Ireland that fundamental right.”
TUV leader Jim Allister told the rally that the Northern Ireland Protocol was “furthering the objective” of a united Ireland.
Il a dit: “How could it be otherwise when, under the protocol, Great Britain is regarded as a third or foreign country in trade terms?
“The stark reality, as spelled out in the Court of Appeal judgment on the protocol, is that the protocol “subjugates” Article Six of the Acts of Union, which guarantees freedom of trade within and between the constituent parts of this United Kingdom.”
He said that checks on goods at Northern Ireland ports meant that freedom of trade had been “fettered”.
Mr Allister added: “All of this is with the political intent that once you create an all-Ireland economically, it is but a short step to a political all-Ireland.
“That is why all unionists must unite and resolutely oppose the iniquitous protocol.”
The Castlederg rally is the latest in a series which have been taking place across Northern Ireland outlining unionist and loyalist opposition to the post-Brexit protocol, which sees additional checks on goods arriving into Northern Ireland from Great Britain.
It is strongly opposed by unionists as a border in the Irish Sea.
Protesters, including a number of bands, met at the Orange hall in the town before parading to the Diamond and then returning to the hall for speeches.
The rally was also addressed by loyalist activist Jamie Bryson.
Mr Bryson used his speech to call on Ulster Unionist Party leader Mr Beattie to rejoin the demonstrations.
Mr Beattie has said he will not attend the rallies, which he said are raising tensions.
Since then the window of his constituency office in Portadown was smashed, and one of his election posters was left with a noose around the neck outside an anti-protocol protest in Lurgan.