LONDON (AP) — Britain's main opposition party has announced that it backs the U.K. staying in the European Union single market and customs union during a "transition period" after Brexit.

The Labour Party says the ruling Conservative Party's Brexit position — taking Britain out of the EU single market immediately after March 2019, when Britain is to leave the bloc — would be "unnecessary" and "highly risky."

Labour Brexit secretary Keir Starmer said Sunday that his party wants Britain to continue to abide by the terms of its current EU membership during an unspecified transition period, before a final shift to a new Britain-EU relationship.

Starmer added that Labour would leave open the option of Britain remaining a member of the EU customs union and single market for good.