Ireland is prepared to support some of Britain's demands for reform of the European Union, Taoiseach Enda Kenny has said.
In an address to business leaders in London, Mr Kenny catalogued a list of economic and political reasons the UK should stay in Europe and offered to look carefully and constructively at David Cameron's proposals.
"I have always been clear that Ireland will be open and pragmatic when it comes to sensible proposals to improve the EU," the Taoiseach said.
"In general, where the UK seeks reasonable and achievable adjustments, we will be sympathetic and supportive."
Mr Kenny's speech follows a report from an influential think-tank in Ireland last week which warned British withdrawal from the EU would see Irish exports fall by three billion euro (£2.12 billion) a year.
The Economic and Social Research Institute (ESRI), which informs policy-making in Dublin, warned energy costs would spike and business in Northern Ireland and along the border would be worst hit by a so-called Brexit.
The Taoiseach's invitation to the CBI also comes on the eve of the Prime Minister setting out his case for EU reform.
On the close ties between Britain and Ireland, Mr Kenny pointed to the one billion euro of trade between the two countries every week, with the UK exporting more to Ireland than it does to China, India and Brazil combined.
Ireland is the UK's 5th largest market with an estimated 200,000 jobs linked to the exports.
The British market is now the biggest for Irish tourism accounting for almost 50% of all overseas visitors and around one-third of all overseas tourism revenue in the Republic.
Offering a qualified support for the UK position on Europe, Mr Kenny said: "Given the breadth and depth of these overlapping interests, it is perhaps not surprising that Ireland regards the prospect of the UK leaving the EU as a major strategic risk."
He said Brexit is not something the Irish Government wants to "see materialise at all".
"The Irish Government's strong view, backed up by independent economic research published last week, is that a Brexit is not in Ireland's economic interest.
"The research showed adverse impacts across a range of headings including Trade, Energy and the Labour Market. It also debunked the myth that there would be some FDI bonanza for Ireland if Britain left the Union."
Mr Kenny holds talks with Mr Cameron in Downing Street later.
On Northern Ireland issues the Taoiseach said it was extremely worrying that it could be worst hit by Brexit.
"I believe that Northern Ireland can leave the past behind and become a dynamic economy that will benefit not only the UK but the island of Ireland," he said.
"There must also be cooperation to build the island economy through overseas investment, trade, tourism, and utilising a competitive, common corporation tax rate.
"Now is not the time to weaken the cohesive, stabilising influence and outward focus that shared EU membership brings to Northern Ireland."
Mr Kenny noted 2.4 billion euro (£1.7bn) of funding from the EU in the six years to 2013 to help the region as it recovered from conflict.
And on the prospect of a deal being reached this week to revive power-sharing in the Stormont Assembly, the Taoiseach said he was optimistic.