The Society of St Pius X has threatened to expel traditionalist Bishop Richard Williamson if he retained an extremist lawyer with neo-Nazi ties to defend him in a German court.

The head of the traditionalist society, Bishop Bernard Fellay, "has formally ordered Bishop Williamson to abandon this decision and not allow himself to be manipulated by political ideas that are completely unrelated to his mission as a Catholic bishop serving the Society of St Pius X", according to a statement.

"To disobey this order would result in Bishop Williamson being excluded from the Priestly Fraternity of St Pius X," said the statement by the society's secretary general, Fr Christian Thouvenot.