Germany's Roman Catholic bishops have decreed that people who opt out of a "church tax" should not be given sacraments or religious burials.

Alarmed by a wave of dissenting Catholics quitting the faith, the bishops issued a decree on Thursday declaring such defection "a serious lapse" and listed a wide range of church activities from which they must be excluded.

Germans who are officially registered as Catholics, Protestants or Jews pay a religious tax of 8% or 9% of their annual tax bill. They can avoid this by declaring that they are leaving their faith community.

The annual total of leavers, usually around 120,000, rose to 181,193 two years ago as revelations about sexual abuse of children by priests shamed the hierarchy and prompted an apology from Pope Benedict.

"This decree makes clear that one cannot partly leave the Church," a statement said. "It is not possible to separate the spiritual community from the institutional Church."

Official statistics show church taxes brought in about €5 billion (£4bn) for the Roman Catholic Church and €4.3bn for the Protestant churches in 2010. The bishops said the consequences of leaving the church had not been clearly spelled out in the past. Some tried to remain active in their parish or have a religious burial despite leaving the church to avoid the tax.

Catholics who leave can no longer receive sacraments, except for a special blessing before death, the decree states. They cannot work in the church or its institutions, such as schools and hospitals, or be active in church-sponsored associations such as charity groups or choirs.

They cannot be godparents for Catholic children and must get a bishop's permission to marry a Catholic in a church ceremony.

"If the person who left the Church shows no sign of repentance before death, a religious burial can be refused," it added.