In October, Williams will succeed George Carey as the spiritual leader of 70 million faithful of the Anglican Communion worldwide. Dr. Carey is retiring.
"Having been informed of your appointment as Archbishop of Canterbury, I am pleased to extend to you my congratulations and to assure your of my prayers," the Pope said in a message sent after receiving the news while in flight to Toronto.
"I have had the opportunity to know and work closely with your predecessors, Archbishop Runcie and Archbishop Carey, in the shared task of promoting understanding between the Anglican Communion and the Catholic Church," the Holy Father continued.
"I am confident that, with God's help, we can make progress along the path towards unity, in order to experience anew 'How Good and Pleasant It Is When Brothers Dwell in Unity!'" (Psalm 133:1). I send my best wishes for your new and demanding ministry," the papal telegram concluded.