The government has been accused of dragging its heels on promised reforms to zero-hours contracts and the gig economy as legislation to protect workers faces serious delays.

New legislation intended to bolster protections for Britain’s most vulnerable workers will not be ready until the end of the year at the earliest, raising fresh questions about the government’s promise to protect workers’ rights after Brexit.

Whitehall’s newly departed employment tsar, Matthew Taylor, said there was a “deafening silence” from ministers on the landmark employment reforms, in areas such as zero-hour contracts and the gig economy, which were announced by Boris Johnson more than a year ago.

The government pledged to make Britain “the best place in the world to work”. Taylor claims the government’s enthusiasm for the reforms had since “waned”.

While the business department said the government remained fully committed to toughening up the law to protect those in precarious employment, the TUC, the Labour party and senior Conservatives joined Taylor in demanding faster progress.

Sources close to the government said its flagship employment bill – pledged before the UK formally left the EU as the central mechanism to safeguard workers’ rights – was unlikely to be launched until late 2021 or even early 2022. Stakeholders have been told these are the potential times it could be brought to parliament, despite being announced more than a year ago, they said.

The changes to tackle insecure work had been promised in the December 2019 Queen’s speech, a day before the key Commons vote that passed Johnson’s Brexit plan, as the way his government would “protect and enhance workers’ rights as the UK leaves the EU, making Britain the best place in the world to work”.

But in an intervention over the lack of progress,Taylor, who was the government’s director of labour market enforcement until the end of last month, questioned the Conservative party’s desire to safeguard working standards.

“There is still no clarity on what the government intends to do. We have seen a gradual but unmistakable deceleration of the government reform agenda in relation to good work. There was an initial enthusiasm but that has waned, and waned, and waned,” he told the Guardian.

Taylor’s role as director of employment rights remains vacant after his term expired last month. He offered to remain in post unpaid until ministers hired a replacement but was turned down.

A business department spokesman said launching the bill was a matter of securing parliamentary time, adding that “protecting and enhancing workers’ rights is a​n absolute priority for this government.

“We remain ​firmly committed to ​upholding high standards and to delivering legislation that ensures we have an employment framework that is fit for purpose in the 21st century.”

However, MPs, including backbench Tories, have grown unsettled by the lack of progress. The Commons women and equalities committee said last week the bill was vital for protecting female workers disproportionately hit by the pandemic. Caroline Nokes, the group’s Conservative chair, said: “We think it’s important the bill comes forward before the end of June.”

Taylor, a former adviser to Tony Blair who led a government review of modern working practices for Theresa May in 2017, said it was surprising ministers appeared to be dithering at a time when public concern over abuses in the workplace was rising due to the Covid recession.

More than 2.6 million people are forecast to be unemployed by the middle of this year – more than double pre-pandemic levels.

Sources said officials casted around last summer for a refit of the bill to reflect the impact of Covid on the jobs market, but there had been little progress since towards launching it.

In a sign of its unready state, they said key consultations for reforms in the bill – such as a new single enforcement body for employment rights – had yet to be responded to by the government.

While the urgency of tackling Covid had delayed other areas of policy, Taylor said more could have been done and suggested the Tories were increasingly split on how to proceed.

“I suspect they are caught in the horns of a dilemma, in that they have deregulatory instincts you would expect of a Conservative government. And you have a business community very unhappy about Brexit, so they don’t want to be seen to be doing anything that might look like they are putting further burdens on business,” he said.

“We are seeing a government that doesn’t want to abandon its commitment to good work, but also doesn’t want to upset the deregulatory wing of its own party and parts of British business.”

Andy McDonald, the shadow employment rights secretary, said the bill needed bringing forward. “Weak employment rights and almost non-existent enforcement has contributed to unsafe working and economic insecurity that has left the UK with the highest Covid death rate in the world and the worst economic crisis of any major economy,” he said.

Tim Sharp, senior policy officer for employment rights at the TUC, said: “It’s really disappointing we haven’t seen it yet. It seems to give a sense of where workplace rights issues sit in the set of priorities.”

Last month it emerged the government was reviewing options to change workers’ rights after Brexit amid concerns over border disruption for companies and a push by ministers to demonstrate benefits from leaving the EU.

However, the new business secretary, Kwasi Kwarteng, then stage a rapid U-turn late last month, saying the work was “no longer happening within the Department for Business, Energy and Industrial Strategy”.

He added: “I made it very very clear to officials in the department that we’re not interested in watering down workers’ rights.”

Opposition voices are, however, concerned that a review being led by the former Tory leader Ian Duncan Smith into post-Brexit opportunities could be used to recommend watering down employment standards, in a process that is due to report back to the prime minister in April.

Charities said rising unemployment caused by the Covid crisis raised the risk of unscrupulous employers abusing the law. Past recessions have also contributed to growth in low-paid and precarious work that has trapped workers in poverty.

Dave Innes, the head of economics at the Joseph Rowntree Foundation, said ministers delivering on the Queen’s speech promised the government could build a more secure future for workers hit hardest by the Covid recession.

“Only a recovery with a strong focus on good jobs, as opposed to any jobs, will help families who have been pulled into poverty during this crisis, as well as addressing the existing flaws in the labour market which have kept people trapped,” he said.