Sunil Saleem was visiting his sister who was having a baby when a row broke out over her treatment.
It was claimed that a doctor was slow to respond to the needs of Kiran Saleem - with some accusing the medic of discriminating because Kiran was a Christian.
When Sunil complained, reports suggest he was attacked over a 30 minute period and was only given limited treatment prior to his death.
Wilson Chowdhry, chair of the British Pakistani Christian Association, said: "Once again medical professionals have been found breaking the Hippocratic oath. The failure to adhere to international medical ethics should be deeply concerning to the Government of Pakistan as it highlights the failure by the nation to meet international laws for human rights that the nation has ratified.
"A family has been broken and the Christian community demoralised by another failure by a national institution. The systemic prejudice within the states statutory authorities and services are examples of an ongoing genocide which will one day eradicate Christianity from Pakistan if left unchecked.
Police in Lahore are said to be investigating the killing while the British Pakistani Christian Association is raising funds to pay for the funeral and legal costs.
Raising concern for all Christians in Pakistan, Nasir Saeed from religious freedom charity CLAAS, said: "I am very concerned by the government's inactions as perpetrators are continuing to take the law into their own hands and kill innocent people with impunity.
"It is sad that that country that was created with the support of religious minorities has increasingly becoming a minefield for them."
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