Meanwhile, the DUP's Brexit spokesperson says new pledges on Northern Ireland are "fairly meaningless"
The British government has lost another vote in the House of Commons over Brexit.
An amendment put forward by Conservative MP Dominic Grieve has been passed, which means British Prime Minister Theresa May will have to come back to Parliament with a fresh plan within three days if MPs don't support her withdrawal deal next week.
British MPs have resumed their debate on the deal today, after Mrs May dramatically called off a key House of Commons vote on it last month.
There remains widespread opposition to the deal in Westminster - meaning it remains unlikely that Mrs May can get it passed through the necessary parliamentary vote.
The latest vote will increase pressure on Mrs May to have a 'plan B', as the EU continues to insist there will be no substantial changes to the deal currently on the table.
The Democratic Unionist Party (DUP) has rejected the government’s latest attempt to win its support for the Brexit withdrawal agreement.
At the outset of the debate, Mrs May’s deputy David Lidington announced a series of assurances on Northern Ireland aimed at winning the support of more MPs for the deal.
The pledges are due to be included in a written statement that will be published this afternoon.
One of them appears to offer the Stormont assembly a veto on any new areas of law under the backstop.
This morning however, DUP Brexit spokesman Sammy Wilson said the proposals were “fairly meaningless” and will not win his party’s support.
The party continues to prop up Mrs May’s minority government under a confidence and supply agreement.
"We are concerned that this falls far short of what we agreed last December, which was a veto for Stormont on the backstop," said Mr Wilson.
"This says we would be consulted if it were to be introduced, and that if it were to be introduced we would have the ability to stop any new EU regulations.
"These would be outside the scope of the 300 areas of law set out in the withdrawal agreement and of course it's possible that existing EU laws could be extended to new industries which could not be vetoed.
"This is fairly meaningless. We have had detailed discussions with the government and they know this doesn't go near to meeting the requirements."
He confirmed that the DUP plans to vote against the deal next Tuesday – and said he hoped Mrs May would return to Brussels to carry out more negotiations if the deal is rejected.
The EU has already warned that the agreement, which has been accepted by 28 EU Governments including the UK, cannot be renegotiated.
The Irish Government, the EU and the majority of Northern Ireland’s political parties have rejected calls for a veto on the backstop.
Speaking in the House of Commons this morning, Mr Lidington warned MPs that while Mrs May was still seeking assurances in Brussels about the backstop, there is no alternative deal on the table.
"I don't think that the British public are served by fantasies about magical alternative deals that are somehow going to sort of spring out of a cupboard in Brussels,” he said.
"This deal on the table has involved some very difficult give and take on both sides and if you go around and talk to the other EU 27 governments they will say that there are elements of this that cause them some political pain.
"But they are very clear, in conversations I have had with them as well as their public statements, they ain't going to be going back and unpicking this for some brand new brilliant renegotiations.
"So, the choice that people have is this deal or it is no deal or it is, as some MPs advocate, to reverse the 2016 referendum entirely."
The series of pledges on Northern Ireland to be published this morning are expected to be:
Additional reporting by Stephen McNeice