Amber Rudd says May's Brexit deal is best option

Britain's work and pensions minister Amber Rudd said Prime Minister Theresa May's Brexit deal was the best option and the only plan available for leaving the European Union, although she admitted a plan B might be needed.

Members of parliament look set to vote down May's deal on Tuesday, a move which risks hurtling the world's fifth-largest economy into even deeper uncertainty and leaving open a number of possible outcomes including a disorderly Brexit.

"The best deal we have is the one the Prime Minister's put forward," Rudd told BBC radio on Saturday. "There is only one plan."

May has said lawmakers must back her withdrawal deal or face either a painful 'no-deal' exit from the EU or possibly no Brexit at all, but Rudd said a 'Plan B' might be required.

"If it (May's plan) doesn't get through anything could happen: people's vote, Norway plus, any of these options could come forward," she said.

Norway is not an EU member but is in the bloc's single market, which allows for free movement of goods, capital, services and people. 'Norway plus' envisages Britain also staying in the EU's customs union, which Norway is not in.

Some pro-EU lawmakers, including in May's ruling Conservative Party, have also expressed support for a second referendum on EU membership, or 'a people's vote'.

Rudd said that even if May loses Tuesday's vote she should stay on as prime minister.

"There is no question of her going," she said.