Plans to curb immigrants' access to healthcare could create a serious public health risk, Pamela Nash, the chair of the All-Party Parliamentary Group on HIV/Aids said.
"Studies highlight that more than half of new HIV infections are passed on by people who are undiagnosed. Encouraging GPs to carry out immigration checks sends out entirely the wrong message and could be counterproductive," she said.
Labour plans to table a number of amendments to the Bill, which will be debated by MPs today. Under the party's plans it would be illegal for recruitment agencies to target and recruit only foreign workers and for employers to deliberately run shifts for foreign workers or segregate the workplace by nationality.
Employers would also face an increased fine of up to £50,000 for failing to pay the national minimum wage.
The top fine for illegally employing foreign workers would be trebled to £30,000.
The party would also tighten student visitor visas to prevent abuses and require every large firm that hires a migrant worker from outside the EU to offer one apprenticeship "in return".But the Conservatives have attacked that plan saying there could be no guarantee British workers would get those apprenticeships.
Yvette Cooper MP, Labour's shadow home secretary, accused Coalition ministers of failing to address the exploitation of low-skilled immigrants.
"We need a system that is fair for all and a labour market that works for all.
"We need practical measures to close loopholes in the minimum wage, or deal with agencies recruiting only from abroad, or gangmasters exploiting illegal labour."