The Vatican has appealed for the release of more than 200 schoolgirls kidnapped by the Islamist group Boko Haram in Nigeria, voicing its "compassion" and "horror for the physical and spiritual suffering".
Vatican spokesman Federico Lombardi condemned the "terrorists" and said it was "the latest of the horrible acts of violence that have characterised the activity of this group in Nigeria for a long time".
"The total lack of respect for life and for human dignity, including for the most innocent, vulnerable and defenceless people demands an extremely firm condemnation," Lombardi said on Vatican radio.
"This evokes compassion filled with sadness for the victims, horror for the spiritual and physical suffering and for the incredible humiliations that they are being subjected to," Lombardi said.
World powers, including the United States and China, have joined in the search for the kidnapped girls and Nigerian police have offered $US300,000 ($A324,600) for information leading to their rescue.
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Boko Haram militants have killed thousands of people in the country's northeast in a five-year insurgency across Africa's most populous country and top economy.
