LONDON (REUTERS) - British opposition leader Jeremy Corbyn met Prime Minister Theresa May last week and has written her a letter putting forward five demands by his Labour Party on the Brexit deal, his party said late on Wednesday (Feb 6).

In the letter made public on Wednesday, Mr Corbyn said the Brexit deal must include a "permanent and comprehensive" United Kingdom-wide customs union, a close alignment with the single market, "unambiguous agreements" on future security arrangements, and commitments on Britain's participation in European Union (EU) agencies and funding programmes.

The Labour leader wrote that the above demands should be put into law before Britain leaves the EU.

Mr Corbyn also reiterated that there must not be a return to a hard border in Northern Ireland, adding that all steps must be taken to avoid a no-deal Brexit.

Mrs May will respond to Mr Corbyn's letter, on his proposals for a Brexit deal but she has not changed her position that a customs union with the European Union should be ruled out, her spokeswoman said on Thursday. The spokeswoman also told reporters that May was focused on securing changes to the so-called Northern Irish backstop arrangement to prevent the return of a hard border in Ireland in order to try to win the support of parliament for her deal.

Last month, British lawmakers rejected Mrs May's original deal that set out the terms by which Britain would exit the EU. They voted to demand that Mrs May seek changes to the treaty.

Britain is due to leave EU on March 29.

Mrs May is set to travel to Brussels on Thursday to tell EU leaders they must accept legally binding changes to the Irish border arrangements of the divorce deal or face the prospect of a disorderly no-deal Brexit.

London and Brussels are arguing over whether the Brexit deal clinched in November can be changed, raising the possibility of a delay to Brexit, a last-minute deal or a no-deal exit.