Boris Johnson's plan to exempt air passengers from the Irish Republic from quarantine is unlikely to be reciprocated, say sources.
Passengers arriving in the UK by air will be presumed to be carrying coronavirus and will be required to self-isolate in a private dwelling for two weeks.
There will be an exception for passengers from the Republic.
But Dublin sources have stressed Irish health authorities cannot extend any such courtesy to air travellers arriving from Great Britain in the Republic.
This means British people coming to the Republic, or Irish people returning from a visit there, will have to give their details and self-isolate for 14 days.
"The way the UK is counting cases and deaths is very different than this jurisdiction and they are still not testing in the community. Yet, Britain still has the worst situation on coronavirus in the world right now," a well-placed source said. "We are just not in a position to reciprocate in all the circumstances," the source added. The same obligation will not apply to people coming to and from Northern Ireland.
There is also uncertainty around what will happen in the case of people flying into Dublin and then crossing the border into Northern Ireland, thereby undermining the quarantine measures.
Meanwhile, the body representing Northern Ireland's hospitality industry has said quarantine restrictions for air travellers will make a bad situation worse for the tourism sector.
Colin Neill, chief executive of Hospitality Ulster, said: "It will have further implications for rebuilding tourism. We are already in a difficult place and that will make it worse.
"That said, health has to drive everything at the minute and if scientists are saying it has to be done, well yes, but for how long?
"The biggest challenge we have at the minute is planning. We aren't saying we want to open now, but we need a timeline so we can plan and so we can see what money we need to survive.
"If we do it (the quarantine) other countries will reciprocate and then how long do they have that ban? If it needs to be done, it needs to be done within a timeframe."
Belfast International Airport said it was not consulted on the Government's plans. A spokeswoman said it feared the proposal would have a "serious effect" on the airport and the region's economy.
"We have received no official confirmation on the Government's plans so we are unable to make a specific comment," she said. "However, we can confirm that Belfast International Airport has not been consulted on this move.
"We have written to government asking for clarification and outlining the serious effect this would have not only on our business but also, and more importantly, on the economy of Northern Ireland."
Although Belfast City Airport does not operate any flights from outside the UK, a spokesperson said it would abide by whatever regulations the Government puts in place.