Tories accused of cowardice and dishonesty in Brexit vote row
Theresa May stood by under-fire Chief Whip Julian Smith as the Tories were accused of cowardice and dishonesty over murky Commons voting tactics.
The Prime Minister again insisted that Mr Smith had made an "honest mistake" when he ordered Tory Party chairman Brandon Lewis to break a pairing agreement with an MP on maternity leave during a crucial Brexit vote.
Tory sources said the move had been an error but admitted the Whips' Office had considered breaking other pacts during the vote.
Labour stepped up its calls for the PM to sack the two men if they failed to resign.
Deputy leader Tom Watson said: "It is unbelievable that the Prime Minister has repeated the desperate and blatantly untrue excuses made by her party chair and Chief Whip.
"This is a serious issue that goes beyond efficient administration in the House of Commons. This is about public trust in politics. At such a crucial time for our country, people expect candour and decency, not cowardice and dishonesty.
"Theresa May was right to call the Tories the 'nasty party', and nothing has changed.
"From forcing seriously ill MPs into the Commons in their wheelchairs, carrying sick buckets, to cheating a new mum out of her vote, this Government is rotten to its core.
"If Brandon Lewis and Julian Smith, two generals of the nasty party, don't have the honour to resign, the Prime Minister should find the strength to sack them."
Former deputy prime minister Lord Heseltine, a pro-EU Tory, said "there is no excuse for breaking one's word".
He told BBC Radio 4's World At One: "It is to me unthinkable that the biggest peacetime political disaster of my life is being forced through the House of Commons with any device, threat, chicanery that the Government can turn its hands to."
Northern Ireland Secretary Karen Bradley, a former whip, twice declined to say if his job was at stake.
Ms Bradley said "mistakes happen" in the whips office.
Asked about his future, she said: "As I've said, he has apologised."
Mr Lewis had been "paired" with Liberal Democrat deputy leader Jo Swinson, meaning neither would walk through the voting lobbies.
The decision to delve into dark arts tactics during the knife-edge Brexit battle on Tuesday drew criticism from across the political divide.
Tory former minister Anna Soubry joined Labour in calling for Mr Smith and Mr Lewis to resign.
Theresa May insisted they had made an "honest mistake" and had apologised.
Speaking to the Press Association during a visit to Northern Ireland on Thursday, the Prime Minister said: "It was an honest mistake and they have apologised."
The PM repeated the comments when pressed on the issue during a question-and-answer session following a speech in Belfast on Friday morning.
Over the course of the Parliament, 66 pairing arrangements have been broken, with 52 of those at the hands of the Opposition, according to Tory sources.
Conservative whips did consider breaking short-term pairing arrangements - those for MPs who need to be away for another engagement, sources acknowledged.
But they said long-term pairing for maternity and health issues was something they stick to and insisted breaking the agreement with Ms Swinson had been a mistake.
Commons Leader Andrea Leadsom said there would now be a debate on proxy voting, which would end the need for pairing, in September.