Sinn Féin leader Mary Lou McDonald has said companies cannot be trusted to provide employees with safe working conditions when Covid-19 restrictions are lifted.
In a letter to Taoiseach Leo Varadkar, which has been seen by the Irish Independent, Ms McDonald said the government must introduce strict new rules for businesses reopening after the lockdown.
"It is critical that the Government sets out what health and safety procedures will be in place to protect workers, alongside the opening of workplaces," she wrote.
"We all know that self-regulation will not work and there needs to be a strong compliance system in place which supports, and has resources to carry out, necessary monitoring," she added.
The Sinn Féin leader said she was aware of employers who contacted employees last weekend in anticipation of returning to work next week.
The letter was sent ahead of a meeting of party leaders due to take place this week.
Ms McDonald, who recently recovered from the coronavirus, also accused the Government of wrongly raising the public's expectation over the lifting of restrictions.
"We all want to see people back at work, schools reopening and to have renewed contact with our families; however, I am concerned that the Government has increased expectation regarding the lifting of restrictions on May 5," she said.
"In my view this is a mistake which has caused a lot of confusion and anxiety.
"The HSE has conceded it will not be in a position to ramp up testing and tracing until the middle of May and the ability to test, trace and isolate is critical to the easing of restrictions in a planned, safe way."
She said the lifting of restrictions must be done gradually and there should be an all-Ireland approach.
Ms McDonald also told the Taoiseach there should be a "fair recovery" after the pandemic and said healthcare workers should be paid better.
"It's not enough to applaud our healthcare workers, we must pay them properly," she said.