People with strong religious beliefs are free to express their faith privately but cannot insist their employer accommodate it, a landmark hearing on religious freedom has heard.

Four British Christians who claim they were discriminated against because of their faith have taken their fight to the European Court of Human Rights.

The issue has caused difficulties in some NHS organisations, with some debate around the extent to which the freedom to display religious symbols should be balanced with hygiene rules which ban jewellery for those in clinical roles.

The court in Strasbourg, France, heard the cases of two workers forced out of their jobs after visibly wearing crosses, a Relate therapist sacked for saying he might not be comfortable giving sex counselling to homosexual couples, and a Christian registrar who wishes not to conduct civil partnership ceremonies.

They argue that the actions of their employers contravened articles nine and 14 of the European Convention on Human Rights, which prohibit religious discrimination and allow “freedom of thought, conscience and religion”.

But a lawyer for the Government, which is contesting the claim, argued that their rights are protected in private only.

James Eadie QC, representing the UK Government, told the nine judges that British domestic law struck a fair and compatible balance.

“These four linked cases at their core raise questions about the rights and the limits to the rights of employees to force their employers to alter employment conditions to accommodate the employees’ religious practices,” he said.

“The convention protects individuals’ rights to manifest their religion outside their professional sphere. However that does not mean that in the context of his or her employment an individual can insist on being able to manifest their beliefs in any way they choose.”

He added: “There is no basis for interfering with that conclusion.”

British Airways worker Nadia Eweida, from Twickenham, south-west London, received widespread publicity when she was sent home in 2006 after refusing to remove a necklace with a cross or hide it from view.

An employment tribunal ruled Ms Eweida, whom court documents say is a Coptic Christian originally from Egypt, had not suffered religious discrimination, but the airline changed its uniform policy after the case to allow all religious symbols, including crosses.

Nurse Shirley Chaplin, from Exeter, was moved to a paperwork role by the Royal Devon and Exeter Trust in Devon after refusing to remove a necklace bearing a crucifix.

Gary McFarlane, a Bristol marriage counsellor, was sacked for refusing to give sex therapy to homosexuals and registrar Lillian Ladele was disciplined after she refused to conduct same-sex civil partnership ceremonies in north London.

The four, whose cases have been publicly backed by Lord Carey, the former Archbishop of Canterbury, argue that the actions of their employers contravened articles nine and 14 of the European Convention on Human Rights, which prohibit religious discrimination and allow “freedom of thought, conscience and religion”.