Pope Francis has used Twitter to back an annual anti-abortion rally, the March for Life, which is expected to draw tens of thousands of activists to Washington on Wednesday.
"I join the March for Life in Washington with my prayers. May God help us respect all life, especially the most vulnerable," he said on his Twitter account in a message that was quickly re-tweeted thousands of times.
The Argentinian-born pontiff has some 11.5 million followers on his Twitter account in several languages, @pontifex.
The Washington rally is one of the key events of the pro-life movement in the United States, where abortion is one of the most polarising issues in politics.
Earlier this month, Francis called abortion "horrific", using some of the strongest language on the issue since his election last March.
Francis alarmed some conservatives last September with comments in an interview with a Jesuit magazine suggesting the Church should shake off an "obsession" with such divisive issues as abortion, contraception and homosexuality.
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