TORIES cannot be trusted to strengthen post-Brexit workers’ rights, Labour frontbenchers and unions said as they rallied against Theresa May’s latest tactic to shore up support for her unpopular withdrawal deal today.

A government source confirmed that the Prime Minister is considering backing an amendment to her plan — proposed by a small number of backbench Labour MPs — calling for protections.

The amendment was tabled by Bassetlaw MP John Mann and endorsed by around 20 other backbench Labour MPs of Leave-voting constituencies, who said it would safeguard workers’ pay and conditions after Brexit.

The suggestion would keep EU rules on health and safety, as well as environmental standards.

Ms May is considering supporting the amendment to get her deal over the line after Mr Mann said his proposal could make her plan “more attractive.”

Shadow justice secretary Richard Burgon said there was little enthusiasm among the Labour leadership for the amendment, which he warned would simply provide non-binding cover for Ms May’s agenda.

“Even the noises that are being made in the press by the Conservatives don’t mean any such agreement would be legally binding when it comes to protecting workers’ rights,” he said on BBC Radio 4’s Today programme.

Mr Burgon hit back at Conservative Party chairman Brandon Lewis after the top Tory accused him on Twitter of failing to say what Labour’s plan for Brexit would be 23 times.

In response, Mr Burgon tweeted: “Seems the Tories have discovered memes! Again, as you ask:

1. Vote down your rotten Brexit deal

2. Prevent the right-wing fantasy of No Deal

3. Get a General Election to bring down your terrible government and get a better deal not just with Europe but for all suffering under your government.”

Shadow education secretary Angela Rayner said Ms May’s concession was a “cynical self-interested attempt” by the PM “to save herself” as it is expected that her deal will be roundly rejected by MPs when it goes to the vote next Tuesday.

“I wouldn’t trust the Tories one iota on employee protection, their record is appalling,” she added.

TUC general secretary Frances O’Grady said: “This amendment makes no change to a bad deal for working people’s jobs and rights.

“We’ve been clear that what working people need is a long-term, binding guarantee that their rights will keep pace with those across Europe. The amendment doesn’t deliver that. It doesn’t even provide an adequate guarantee for the rights we already have.

“And since the political declaration isn’t legally binding, there’s nothing to stop a future government from ignoring it altogether.

Unite general secretary Len McCluskey said: “British workers already have among the poorest protections in Europe. This changes nothing.

“The government cannot spend years attacking unions and their members and then expect us to be fobbed off.”

General union GMB warned it was all a “cynical ploy to buy off MPs” and general secretary Tim Roache said any MP who thinks such an amendment makes “a bad deal good needs to have a serious word with themselves.”

“These assurances are meaningless at best, and at worst a cynical attempt to use workers’ rights as a bargaining chip for self-preservation.

“To be clear – this doesn’t guarantee workers a single thing.”

Usdaw shop workers union general secretary Paddy Lillis added: “We have little faith that this government would deliver on any promises and we oppose MPs accepting anything short of legal guarantees.”