UPDATE 1-Dutch PM Rutte says path to Brexit breakthrough unclear

Dutch Prime Minister Mark Rutte said the path to a breakthough on Brexit remained elusive, and he did not know what his British counterpart Theresa May meant when she said on Friday that only "one more push" was needed to reach a deal.

With just three weeks left before Britain is due to leave the European Union, May used the expression in a last-ditch appeal to the European Union and a deeply divided domestic parliament. "The Brexit date is getting ever closer. The ball is still rolling toward the cliffs of Dover. I am worried (it)... is rolling the wrong way," Rutte told journalists, adding he would speak with May on Friday evening.

Rutte said May's plan to amend her withdrawal agreement to secure parliamentary approval was unclear, and reiterated that British "red lines" for talks with the EU were preventing a solution. "To be clear: we are running out of options. The British government and parliament must make up their minds," he said. "If the British keep asking for a time limit for the (Irish) backstop that's not going to work."

London and Brussels are at loggerheads over the backstop, an insurance policy to prevent the return of border controls between Northern Ireland and Ireland - the only land frontier between the United Kingdom and the bloc. Asked what the solution to the stalemate could be he answered: "I don't know".

He then suggested a supplementary, non-legally binding letter from European Council President Donald Tusk and other senior EU officials on details of the deal might help move negotiations forward. The Netherlands, the world's fifth largest exporter, is among nations most vulnerable to the economic disruptions that a disorderly British departure would cause. (Reporting by Stephanie van den Berg and Bart Meijer; Writing by Anthony Deutsch; Editing by Kevin Liffey and John Stonestreet)