Sinn Fein has branded government plans to only recruit new Border Force officers who hold a British passport as "naked discrimination".
Conor Murphy MLA was responding to the news that 21 Border Force posts being advertised for Belfast required applicants to hold a UK passport.
Those who hold Irish passports only cannot apply, the Irish News reported.
Mr Murphy said: "With this British Border Force recruitment drive, the British Government are clearly planning to impose their hard Brexit border across the island of Ireland.
"It shows that the Tories see a hard border as the predetermined outcome of the Brexit negotiations despite the fact they have already agreed to an option to avoid it."
Mr Murphy claimed it also pointed to "the Tory-DUP pact's growing disregard for the Good Friday Agreement, which allows citizens to determine their own identity free from discrimination". He said: "Not only are they ignoring the democratic expressions of Irish citizens, they're also actively excluding them by reserving these posts solely for citizens with British passports.
"This is naked discrimination of a public sector position, and a statement of intent to impose a Brexit border in Ireland. Sinn Fein reject both these discriminatory plans unreservedly."
Meanwhile, Sinn Fein leader Mary Lou McDonald TD accused the government of placing its deal with the DUP at Westminster "above the need to re-establish the Executive".
Ms McDonald said during a visit to Belfast: "The British and Irish governments have said over recent days that they want to see a process up and running to restore the institutions.
"However, it is absolutely clear that the British government has placed their deal with the DUP above the need to get government back up and running in the north and delivering rights for citizens.
"It's clear the British government is playing for time, and it's clear that Karen Bradley [Secretary of State] has failed to introduce any new momentum into the process. The governments need to act to end the DUP's denial of rights enjoyed by citizens everywhere else on these islands, including Irish language rights, the right of LGBT citizens to marry the person they love, and the right to a coroner's inquest."
She said the two governments should convene the British Irish Intergovernmental Conference in order to resolve outstanding issues.