BRUSSELS (REUTERS) - The EU is open to "alternative arrangements" to the Irish backstop - as cited in a key British legislative proposal on the Brexit treaty - but for now no such alternatives exist, a senior EU negotiator said on Monday (Jan 28).

Referring to an amendment to Brexit legislation proposed by a supporter of British Prime Minister Theresa May, Mr Graham Brady, who wants "alternative arrangements", deputy chief EU negotiator Sabine Weyand said that the withdrawal treaty that has been rejected by UK lawmakers already contained that possibility.

"We are open to alternative arrangements" on the Irish border, she told a conference. "The problem with the Brady amendment is that it does not spell out what they are."

"It's not a criticism of them because they don't exist," she added.

However, she urged British lawmakers not to view the backstop, which would keep the UK in a customs arrangement with the EU until a better way is found to avoid checks on the Irish border, as pre-judging how a better trade deal may be struck.

"The backstop is not a prerequisite for the future relationship," she said. "We are open to alternative proposals."

She also said if and when EU leaders discuss delaying Brexit by agreeing to extend negotiations, they "will require certain elements of information... and one of them is the purpose of extension".

"They would want to be reassured that at the end of the extension, there will be clarity," she said. "The idea of going into serial extensions is not very popular on the EU side."