In an apparent swipe at the DUP, Mr Martin added damage over weaponising Brexit could go “much further”.
He said: “When this approach is followed in relation to UK-EU relations the damage it causes is primarily economic.
“When it involves misrepresenting the arrangements for Northern Ireland the damage can go much further.”
As part of the UK and EU’s Brexit trade deal, the Northern Ireland Protocol means European checks and trade rules apply to goods entering the province from Britain.
Northern Ireland also remains part of the EU’s single market under the Protocol, which avoided the creation of a land border in Ireland – a key part of the 1997 Good Friday Agreement.
Northern Irish unionist leaders and groups have voiced outrage over the Protocol, and have accused the Irish Government of failing to listen to the concerns of businesses and consumers in the province.
DUP leader and Northern Ireland’s First Minister Arlene Foster said at an In Conversation online event earlier this month: “What we have is a completely disproportionate situation where trade between Great Britain and Northern Ireland has been severely disrupted.”
