The British government has suffered a second Brexit defeat in the House of Lords as peers backed, by 366 votes to 268, calls for a “meaningful” parliamentary vote on the final terms of withdrawal.
Backing the move, former deputy PM Lord Heseltine said Parliament must be the “custodian of national sovereignty”.
Ministers said it was disappointing and they would seek to overturn the move when the bill returns to the Commons.
The previous defeat was on the issue of guaranteeing the rights of EU citizens.
After a three-hour debate on Tuesday, for the second time in a week peers amended the legislation that will authorise Theresa May to notify the EU of the UK’s intention to leave and pave the way for official Brexit talks to begin.
The turnout in the Lords for the vote was the largest since 1831, according to Parliament’s website. The amendment, which was carried by a majority of 98, would require the final terms of the UK’s withdrawal from the EU to be put to separate votes in the Commons and the Lords.
Some peers believe this would amount to a veto but ministers insist the UK would leave the EU anyway irrespective of whether it was approved or not.
Among 13 Tory peers to defy the government and vote in favour of the amendment were veteran Europhile Lord Heseltine and former ministers Lord Deben and Viscount Hailsham.
The issue will now return to the Commons to be reconsidered by MPs, who have already rejected calls for the “meaningful vote” clause to be included in the legislation, saying verbal guarantees given by government on parliamentary scrutiny are sufficient, reports the BBC.