An anti-Brexit protester carries flags opposite the Houses of Parliament in London, Britain, May 10, 2018. REUTERS/Hannah McKay

LONDON (Reuters) - The legislation underpinning Britain’s exit from the European Union will return to the House of Commons for more debate next month, British media reported on Wednesday, after the government suffered a series of defeats on plans to leave the trading bloc.

Britain’s upper house of parliament, the House of Lords, has inflicted 15 defeats on the legislation, including on core Brexit issues such as whether Britain should leave the EU’s single market and customs union.

A journalist for the Sun newspaper said the legislation will return to the Commons in “early to mid June” and members of the ruling Conservative party will be instructed to oppose remaining in the single market and customs union.