A controversial medical bill that makes it a crime for doctors to provide emergency first aid without government authorisation has come into force in Turkey despite an outcry from rights groups.

Under the legislation that was approved by President Abdullah Gul on Friday, those convicted could be imprisoned for up to three years and face fines of nearly $1m from January 18.

Critics fear it could be used to bar doctors and medical workers from treating protesters wounded in anti-government demonstrations as reportedly happened during mass street protests in June last year.

The US-based Physicians for Human Rights (PHR) branded the legislation another attempt by the government of Prime Minister Recep Tayyip Erdogan to quash dissent.

"Passing a bill that criminalises emergency care and punishes those who care for injured protesters is part of the Turkish government's relentless effort to silence any opposing voices," PHR senior medical adviser Vincent Iacopino said.

"This kind of targeting of the medical community is not only repugnant, but puts everyone's health at risk," he said in a statement on the PHR website.

The legislation, drawn up by the ruling Justice and Development Party (AKP), bars medical professionals from working outside state health institutions and is aimed at preventing doctors from setting up private clinics for example.

Medical professionals who break the law would face up to three years in prison and be fined up to $985,000 (728,000 euros).

Political protesters

Last month, the United Nations had also raised concerns about the bill and urged the government to reconsider it.

"If adopted, it will have a chilling effect on the availability and accessibility of emergency medical care in a country prone to natural disasters and a democracy that is not immune from demonstrations," UN Special Rapporteur on the right to health, Anand Grover, said in a statement.

"Enacting laws and policies criminalising provision of medical care to people challenging state authorities, such as political protesters, will certainly deter healthcare workers from providing services due to fear of prosecution," he said.

During the unrest which gripped the country last year, the Turkish doctors' association repeatedly accused government forces of preventing medics from treating injured people.

At least six people were killed and about 8,000 hurt in nationwide clashes between police and protesters who took to the streets in a wave of public opposition to Erdogan.

After 11 years in power, Erdogan is accused of becoming increasingly authoritarian and of trying to impose greater government control and his conservative religious values on all sectors of the traditionally secular society.