Owen Paterson, former Northern Ireland secretary, said electronic gadgets were now able to take the place of physical borders for commercial traffic.
The Irish government wants Brexit talks to include a clause that there will be no change on the border and there are fears that it will veto any clauses that do otherwise.
Mr Paterson said it was disappointing.
"Obviously the Irish could be very influential. Any threats to veto would be most unfortunate," he said.
"There are already borders between the two, currency VAT and corporation tax for example. I have been visiting Northern Ireland and Ireland for 10 years and have talked to the government and opposition in Dublin and to businesses on both sides of the border. No one at any stage has said to me that this should be a problem."
"There are electronic invoices being used currently that take account of differences in tax and currency and it is simple to add another line for customs.
"With good will it should not be a problem. A hard border is completely impractical and will not happen."
"Everyone is getting very het up which is disappointing. There are extraordinary good relations between Ireland and Northern Ireland, better than it has been many years."
Mr Paterson said that only five per cent of goods were exported from Northern Ireland and Ireland and only just over one per cent in the other direction.
"There is absolutely no question of building a hard border, that is a very old fashioned view. Everything can be done with modern, electronic business technology and the trusted trader scheme. It is not complicated if there is good will."