The bill to trigger the Brexit process has passed its first hurdle
Calls for Britain to guarantee the rights of European Union nationals living there have been defeated in the House of Commons.
A Tory rebellion meant the amendment to the Brexit bill was stifled.
It had been brought by former UK Labour leader Harriet Harman to ensure that all EU citizens living in the UK on June 23rd - the date of the referendum - would have their right to stay protected.
But the amendment was defeated by 332 votes to 290, a majority of 42.
Amber Rudd, the UK's Home Secretary, had written to Tories to reassure them that the bill would "not change our immigration system".
Just three Tory backbenchers - Ken Clarke, Tania Mathias and Andrew Tyrie - backed the amendment.
There are also concerns for the Good Friday Agreement.
The UK Labour Whips' Office in the House of Commons tweeted that defeat of the amendment means agreements in the Good Friday Agreement could be broken:
Tories defeat amendment 86 that requires that Article 50 does not break agreements in the Good Friday Agreement #Brexit 288 - 327 maj 39— Labour Whips (@labourwhips) February 8, 2017
While MPs have approved the bill giving the British Prime Minister Theresa May permission to trigger the Brexit process.
At its third reading, the final Commons stage, the European Union (Notification of Withdrawal) Bill passed by 494 votes to 122 - a majority of 372.
It must now go the House of Lords before Mrs May can invoke Article 50, which she has promised to do by the end of March.
A total of 52 Labour MPs voted against triggering Article 50, defying the orders of their party leader Jeremy Corbyn - more than the 47 who did the same at last week's second reading.
Former chancellor Ken Clarke was the only Conservative to vote against the bill.