DUBLIN (Reuters) - Neither of Britain’s proposed future customs arrangements with the European Union are workable, Irish Prime Minister Leo Varadkar said on Tuesday, dismissing the option favored by hardline Brexiteers with a comic aside.

Michel Barnier, the European Union's chief Brexit negotiator, and Ireland's Taoiseach Leo Varadkar attend an all All-Island Civic Dialogue on Brexit in Dundalk, Ireland, April 30, 2018. REUTERS/Clodagh Kilcoyne

With the Irish Republic to have the only EU land border with Britain after Brexit, Varadkar repeated a warning that failure to achieve genuine progress on the customs issue by next month would cast doubt on sealing an overall withdrawal agreement by an October deadline.

Under pressure from the EU to move forward with talks on the future partnership that will follow its exit from the bloc, Britain must first settle on a customs proposal to present to skeptical negotiators in Brussels.

But Prime Minister Theresa May’s cabinet is divided, with some pro-Brexit ministers openly dismissing what is believed to be her preferred option - a customs partnership under which Britain would collect tariffs on goods entering the country on the EU’s behalf.

They favor a streamlined customs arrangement known as maximum facilitation or “max fac”. Under this proposal, companies on an approved list of “trusted traders” would be able to cross borders freely with the aid of automated technology.

Neither idea has found favor with the 27 countries remaining in the EU, which insist that Ireland’s border with British-ruled Northern Ireland must remain free of controls after Brexit.

“Certainly the customs partnership, as proposed by the UK last June, isn’t workable, that’s the view of the (EU) taskforce and the EU27 and has been rejected, but I do think the customs partnership is closer to being made workable than this proposal of ‘max fac’,” Varadkar told parliament.

Varadkar joked that he had misread the option, thinking it was some kind of cosmetic. “Certainly I haven’t seen any detail to date to indicate to me that such a solution would be as functional as make-up or deodorant,” he said.

Varadkar echoed comments made by the EU’s Brexit negotiator Michel Barnier on Tuesday that little progress had been made in recent weeks and repeated his own recent warning that there was a real risk of the sides failing to reach a withdrawal treaty by October.

The EU and Dublin insist the treaty must lock in a backstop arrangement in case future customs arrangements do not remove the need for controls on the intra-Irish border.

London signed up for this in March but disagrees with the EU’s proposals and is being pressed to come up with an alternative means of achieving it before an EU leaders’ summit in June.

“For June, we do want to see real and meaningful progress. If we don’t see that in June, then we have to ask serious questions as to whether a withdrawal agreement in October will be possible at all,” Varadkar said.