Brussels/London - British Prime Minister Theresa May is due to visit Brussels, an EU spokesman has announced, after she vowed to seek last-minute changes to the Brexit divorce deal aimed at securing its passage through parliament.

May's government has hashed out a Brexit deal with the European Union aimed at ensuring a smooth transition when Britain leaves the bloc on March 29. But British lawmakers have rejected the deal, largely due to provisions guaranteeing an open border on the island of Ireland.

"Pragmatic" Brexit deal

May has said she would return to Brussels seeking a "pragmatic" Brexit deal based on alternative arrangements to the so-called backstop to ensure that no hard border emerges between Northern Ireland and the Republic of Ireland.

The EU has insisted however that the withdrawal deal struck with London cannot be renegotiated.

The EU's position is "clear," said European Commission spokesman Margaritis Schinas, adding that they would wait for May to "present to us her ideas for the way forward."

Commission President Jean-Claude Juncker is due to hold talks with Irish Prime Minister Leo Varadkar, before seeing May, Schinas has noted.

Northern Ireland

Meanwhile, May was due to visit Northern Ireland - which will leave the EU with the rest of the United Kingdom - and reassure people there that her Brexit deal will command their "broad support."

"I know this is a concerning time for many people here in Northern Ireland," May is set to say according to a preview of her speech.

"But we will find a way to deliver Brexit that honours our commitments to Northern Ireland," she was expected to tell regional business leaders.

May was expected to promise that she would find a solution that "secures a majority in the Westminster Parliament, which is the best way to deliver for the people of Northern Ireland."

A week ago, a narrow majority of lawmakers in parliament's main elected house, the Commons, backed May's plan to renegotiate the backstop protocol in the withdrawal agreement.

But minutes after the vote, European Council President Donald Tusk issued a statement insisting the withdrawal agreement, including the backstop, "remains the best and only way to ensure an orderly withdrawal of the United Kingdom from the European Union."

May has promised to report back to parliament on her negotiations with the EU on February 13, when lawmakers are expected to hold a second vote on the Brexit deal after having rejected it by a huge margin on January 15.