Tougher regulations are now in place for gangmasters
The fifth anniversary of the deaths of 21 Chinese cockle pickers at Morecambe Bay is being marked.
At least 21 people drowned when they were cut off by the tide in treacherous weather at Hest Bank, Lancashire, on 5 February 2004.
A gangmaster was jailed over the deaths and deported to China.
Prime Minister Gordon Brown said the deaths showed "the awful human cost" of unregulated work, illegal migration and trafficking.
The government "will do whatever it takes to stamp out human trafficking and prosecute employers who persistently employ illegal immigrants", he said.
A Gangmasters Licensing Authority (GLA) was set up by the government after the Morecambe Bay tragedy.
It will be setting tougher sanctions and standards for gangmasters from April.
A total of 23 cockle pickers are believed to have died at Morecambe
They include changes which will increase the likelihood that a gangmaster who ill-treats workers will have his licence revoked immediately.
Widening investigations into the background and track record of those involved in the licensed business are also planned.
All of those who died at Morecambe were illegal immigrants from China, aged between 18 and 45.
Gangmaster Lin Liang Ren, who was based in Liverpool but originally from China, was found guilty of the manslaughter of 21 cockle pickers in March 2006.
It is thought that bodies of two victims have not been found.
Lin Liang Ren and his Chinese girlfriend Zhao Xiao Qing and cousin Lin Mu Yong, both from Liverpool, were also convicted at Preston Crown Court of helping cockle pickers to break immigration laws.
The GLA was set up to protect workers in agriculture, shellfish gathering and food processing and packaging.
There are approximately 1,200 gangmasters licensed by the GLA.
The illegal workers were employed by gangmasters