UKIP Home Affairs spokeswoman Jane Collins MEP said there was "no need for a fundamental risk to Brexit from the DUP because the border with Northern Ireland and EIRE can go back to pre 1993 rules."
"The special status of Irish nationals in UK law predates the EU," she said, warning, "This must not be used as an excuse to derail last year's vote."
"Since the creation of the Common Travel Area there has never been a need to show a passport to cross that border aside from during times of military necessity so as long as there are border controls between the two islands then the UK can have proper Brexit.
"The DUP should avoid derailing the democratic process when their main concern can be addressed separately and they would be wise not to follow the strategy of the SNP by being the dog in the manger.
"However it seems obvious now that in order to keep the wishes of the majority of the people who voted in the referendum last year we need a strong UKIP to keep them on track."
The Common Travel Area (CTA) is a special travel zone between the Republic of Ireland and the UK, Isle of Man and Channel Islands. It dates back to the establishment of the Irish Free State in 1922.