The chair of the Revenue Commissioners has said he is "almost 100% certain" there will be no new customs posts along the Irish border after Brexit.

Niall Cody categorically rejected reports that it was actively looking for locations to establish new checkpoints.

The speculation, which he blamed on an early contingency paper from a "medium ranking" official, has led to landowners along the border directly offering him sites for sale.

But Mr Cody told the Oireachtas Finance Committee: "We are not planning customs posts."

The 498km border between the Republic and Northern Ireland will become an EU/UK frontier after Britain pulls out of the European Union.

A hardening of the border, which has become virtually invisible as a result of the peace process, could threaten peace and prosperity on the island, it has been warned.

However, Mr Cody said an ongoing analysis of cross-border trade increasingly shows that most goods transported between the jurisdictions will not need to be physically checked.

Much of it is agri-food and construction related, and can be documented online.

There are also existing Revenue offices in border counties where traders can carry out their necessary paperwork.

"I'm practically 100% certain we will not be providing new trade facilitation bays in whatever parts of Donegal, Monaghan or Cavan," he said.

Mr Cody also told the parliamentary committee that Revenue is not negotiating with HM Revenue and Customs in Britain on post-Brexit arrangements.

It was assessing all the implications and options, while upgrading its IT systems and recruiting more staff, as it prepared for the outcome of the political negotiations, he said.

Earlier the committee heard that cross-border trade could cost businesses around €400m in compliance costs after Brexit.

That figure is separate to customs tarriffs.

Carol Lynch, a partner with BDO Ireland, told the committee that a charge of €100 per movement would likely apply.

This would be an administrative cost to be paid by the businesses, to an agent, in order to complete an import declaration. 

Fianna Fáil's finance spokesman Michael McGrath said this could place a significant annual cost on businesses. 

He estimated that when you apply this charge to all of the movements that occur across the border each year it amounted to around €400m.