LONDON (Reuters) - Prime Minister Theresa May was dealt a new defeat by Britain’s upper house of parliament on Wednesday over her Brexit plans, this time in a challenge to the government’s push to adopt wide-ranging powers to amend laws.

Britain's Prime Minister Theresa May attends the unveiling of the statue of suffragist Millicent Fawcett on Parliament Square, in London, Britain, April 24, 2018. REUTERS/Hannah McKay

The defeat is the latest in the House of Lords for May and her Conservative government as parliament debates the EU withdrawal bill which will sever ties with the European Union and pave the way for Britain to leave in March next year.

The vote can be overturned by the lower house, the House of Commons, but underscores the deep divisions over Brexit across parliament and could encourage lawmakers hoping to derail May’s plans to forge a new relationship with the EU.

While many of the defeats were expected, it is the rifts over whether to remain in a customs union with the EU that have taken center stage. A new debate on this is scheduled in the Commons for Thursday, adding to the pressure on May.

After Wednesday’s defeat over plans to adopt the so-called Henry VIII powers, which are named after the 16th century monarch who ruled by proclamation but are seen as a power grab by opposition parties, the government was expected to offer peers some concessions on their more detailed objections.

“This House has a responsibility not to give the executive more power than is necessary,” Lord (Peter) Goldsmith told peers before they voted.

The Lords voted 349-221 in favor of an amendment to change the wording of the bill so that instead of ministers being able to use the Henry VIII powers where they consider it “appropriate”, they would have to prove it was “necessary”.

The government has said it needs the powers to be able to meet a tight deadline to effectively “copy and paste” EU rules and regulations into British law by the time of Brexit.

The defeats, while embarrassing, have so far failed to shake the government, but after being debated in the Lords, the bill will return to the Commons, where lawmakers will decide whether to keep the amendments or overturn them.

Earlier, Brexit minister David Davis told lawmakers he expected parliament to uphold the government’s policy “for good reason”, and again said that Britain would leave the EU’s customs union after Brexit in favor of a new trade agreement.