DUBLIN (Reuters) - Ireland is prepared for a 12-fold increase in the number of import and export declarations made by local companies after Brexit, the head of the state agency responsible for customs checks said on Tuesday.

Slideshow ( 2 images )

With close trading links to its nearest neighbour, Ireland’s export-focused economy is considered the most vulnerable among remaining European Union members to the impact of Britain’s departure from the bloc.

The number of firms dealing with customs could surge to as many as 100,000 from 17,000 last year, requiring 20 million annual declarations, if Britain is no longer a member of the EU’s customs union, the chairman of Ireland’s Office of the Revenue Commissioners said.

“It will present a significant challenge for many of those businesses who do not have any experience of third country trade and what it entails,” Niall Cody told a parliamentary committee, adding the agency will have 400 additional staff in place by the end of March to deal with the workload.

It had initially hoped to phase in the 600 new staff that will ultimately be required by the end of 2020, on the assumption that there would be a transition period, but sped up the recruitment as the risk of a no-deal Brexit increased.

Cody said the tax authority was not planning for the return of customs posts to the border between EU-member Ireland and Northern Ireland, which will be the United Kingdom’s only land frontier with the bloc after its departure.

The question of how to keep the seamless border open after Brexit is proving a major hurdle in ratifying the EU divorce deal in London and the Irish government insists it will not countenance making contingency plans for the return of a hard border if no deal can be agreed.

Police on both sides of the border have warned that customs posts could be a target for the small number of militant groups still active in Northern Ireland after a 1998 peace deal ended three decades of violence in the province.

“The government has made clear that its overriding objective is to avoid a hard border on the island of Ireland. Revenue is not planning for customs posts on the land border,” Cody said, adding no preparatory work was being carried out along the 500-km (300-mile) frontier.

He said, however, there would have to be some form of declaration process requiring “significant change”, when asked about the impact of a no-deal Brexit in relation to cross border trade.

“I couldn’t come in here and rule out something forever,” Cody said, when pressed if he could rule out checks, whatever the outcome of Brexit. “There are certain key principles that flow from being a member of the customs union.”