International expert on church unity, Rev Günther Gassmann, a German Lutheran theologian, has urged the Catholic Church to declare officially that its excommunication of Martin Luther no longer applies.

Such a statement, "in these ecumenically less exciting times ... would be a remarkable step and a sign of hope and encouragement," said Rev Günther Gassmann, who was director of the World Council of Churches' Faith and Order Commission from 1984 to 1995, according to an Ekklesia report.

Luther trained as a Catholic monk, but was excommunicated by the Catholic Church in 1521 after refusing to retract teachings the Church judged to be heretical.