LONDON (Reuters) - Britain’s upper house of parliament handed the government its third defeat over Brexit in less than a week on Monday, voting down plans not to retain EU rights in national law before Britain leaves the bloc.

A pigeon flies ahead of Britain's Prime Minister Theresa May as she arrives at a service at St Martin-in-The Fields to mark 25 years since Stephen Lawrence was killed in a racially motivated attack, in London, Britain, April 23, 2018. Victoria Jones/Pool via Reuters

The defeat is one of several Prime Minister Theresa May’s Conservative government is expected to suffer in the House of Lords as parliament debates legislation which will enact Britain’s exit from the European Union in March next year.

The vote can be overturned by the lower house, the House of Commons, but shows the deep divisions over Brexit across the Houses of Parliament and could encourage lawmakers hoping to derail her plans.

The defeat -- over ensuring the political, social and economic rights protected by the European Charter of Fundamental Rights are replicated in British law -- follows a vote by the Lords that challenged her plan to leave the EU’s customs union.

Last week’s defeat, the first of two on that day, increased pressure on May to reconsider her refusal to remain in a customs union with the EU.

On the charter, Lord (David) Pannick, author of the amendment, told peers he feared the government was doing away with it because ministers might want to dilute the protections it offers.

“I fear that the government is seeking to make an exception for rights under the charter because the government is suspicious of the very concept of fundamental rights,” he told the House of Lords.

Arguing against the amendment, Lord (Richard) Keen said by retaining the charter, Britain would be opening up to being influenced by “foreign law” that could to lead to “constitutional outrage”.

The government says the rights the charter protects are already covered by British law and May’s spokesman said earlier on Monday the withdrawal bill, which was approved by the House of Commons before being sent to the upper house, was the best way of providing “the smoothest possible Brexit”.

The defeats, while embarrassing, have not so far shaken the government, but after being debated in Lords, the bill will return to the House of Commons, where lawmakers will decide whether to keep the amendments or overturn them.