The re-elected General Workers' Union president, Salvu Sammut, yesterday dedicated nearly half his speech at the congress to a fierce attack on illegal immigrants, claiming they were "taking jobs from Maltese workers".
Mr Sammut said Malta may be forced to take measures which were not necessarily "just and humane" to solve the illegal immigration crisis.
Alternattiva Demokratika chairman Harry Vassallo walked out of the congress as a sign of protest, later condemning Mr Sammut's comments as inflammatory and unacceptable coming from the president of the country's largest trade union.
"First we had Maltese prostitutes, then we had Russian prostitutes and now we have immigrant prostitutes (prostituti klandestini) who earn double the minimum weekly wage of a Maltese worker," Mr Sammut said.
"We cannot forget the dangers of undetected diseases which may spread among the population."
Mr Sammut said one should not forget the frustration felt by the Maltese who see an illegal immigrant being given precedence at hospital.
"It is understandable when an elderly person, a Gozitan or a person with a disability is given precedence over a Maltese person in a government department. But that an illegal immigrant is given precedence is not acceptable. This is fuelling fear and racist sentiment among people," Mr Sammut said.
"The illegal immigration problem is becoming more acute and alarming and will suffocate us very soon."
Mr Sammut said the circumstances which Malta found itself in were not allowing its people to live up to their reputation as a generous nation.
"The first illegal immigrant who landed in Malta was St Paul. At least he gave us a Christian culture and left after three months. But what good are modern illegal immigrants doing us? They need food, clothing, education and social services and they want to give birth to their races among us," Mr Sammut said.
Reacting to the comments made by Mr Sammut, the AD chairman said a series of popular misconceptions about illegal immigration were being inflated by the extreme right-wing "lunatic" fringe.
"It was impossible to remain and appear to approve in the slightest manner any report that may be made of a speech inflaming racial tension in the country.
"In this situation everybody with a responsibility for leadership should strive to present the facts as they are and to address the challenges in a rational manner," Dr Vassallo said.
It was therefore unacceptable that the president of the country's largest trade union addressing 700 delegates should claim that immigrants were taking Maltese workers' jobs, exposing the Maltese to undetected diseases and jumping the queue at hospital, Dr Vassallo said.
The authorities had for years transmitted the message that immigrants were dangerous criminals by escorting them to hospital in handcuffs.
"These people would greatly prefer not to be treated like criminals whenever they are in need of medical attention and exposed to the irritation and hatred of the Maltese," Dr Vassallo said.
A self-respecting union should have addressed the exploitation and near slavery to which many migrant workers are exposed.
"No self-respecting trade unionist could possibly inflame workers against other workers who are evidently at a greater disadvantage than themselves and who are facing the same illegal exploitation," Dr Vassallo said.
"It is utterly intolerable that the president of the GWU on such an occasion should hint ominously that the solution to the immigration crisis would be 'neither just nor humane'," Dr Vassallo said.