"The date foreseen for the publication of the encyclical of the Pope is Thursday, June 18," said the statement released June 4.
Earlier reports out of Rome said the encyclical was being released June 16.
The head of the Vatican publishing house, Salesian Father Giuseppe Costa, had told reporters in Naples May 30 that publishers from around the world had been asking for the rights to reprint "Laudato Sii" when it is released in mid-June.
"Laudato sii" is the introductory phrase to eight verses of St. Francis of Assisi's famous prayer thanking God for the gifts of creation.
"Praised be you, my Lord, with all your creatures, especially Sir Brother Sun, who is the day, and through whom you give us light," one of the first lines says.
The prayer also praises God for the gifts of "Sister Moon," "Brother Wind," "Sister Water," "Brother Fire" and "Sister Mother Earth."