* Irish PM dismisses May's reference to U.S., Canada border
* N.Ireland to become U.K.'s only land frontier with EU
* Luxembourg PM calls on May to spell out Brexit plans
By Padraic Halpin
DUBLIN, March 5 (Reuters) - The border between the United States and Canada does not provide an example for how to solve the issue of the future border between Ireland and Northern Ireland after Brexit, Prime Minister Leo Varadkar said on Monday.
Northern Ireland is set to become the United Kingdom's onlyland frontier with the EU after Brexit, and Varadkar has urged British Prime Minister Theresa May to spell out her proposals to avoid a hard border returning to the island of Ireland.
Speaking in parliament earlier on Monday, May said that hergovernment would look at many examples of different arrangementsfor customs around the rest of the world, including the borderbetween the United States and Canada.
Varadkar rejected that idea out of hand, however.
"That is definitely not a solution that we can possiblyentertain," he told a news conference after meeting hisLuxembourg counterpart Xavier Bettel in Dublin.
"I visited the U.S. border in August and I saw an armoredborder with physical infrastructure, customs posts and people inuniform with arms and dogs."
Varadkar reiterated that his preference was to retain thecurrent seamless border through a new, deep relationship betweenthe EU and U.K and was also committed to examining specificBritish proposals, but only if they are feasible.
If that is not possible, he said the "very clear draft legalprovision" to implement a backstop allowing the EU to regulateNorthern Ireland's trade would be triggered.
That contingency plan, presented last week in the EU's draftof an exit treaty for Britain, prompted angry reactions inLondon. said that Ireland and Luxembourg needed to standtogether to reduce to a minimum the negative impact from Brexit,describing it as a "game changer" for the EU that is nothingmore than a damage limitation exercise.
He also joined Varadkar in calling on the British governmentfor more detail on its Brexit plans.
"For the moment I can't tell you what I think about TheresaMay's plans, I want to see them, I want to read them. For themoment I don't know what the plans are from the U.K," he said.
"When they were in (the EU), they wanted to have a lot ofopt outs, now that they are out, they want a lot of opts ins...I believe we need solutions because the time is ticking."