Pope Francis on Sunday paid tribute to journalists who have died or been jailed in the line of duty, defending a free press and praising those in the media who courageously report on "humanity's wounds".

Speaking to thousands of people in St Peter's Square for his weekly address and blessing, Francis noted that May 3 will be the United Nations World Press Freedom Day.

"I render homage to journalists who pay in person for this right," he said, citing statistics that 47 journalists were killed and more than 350 jailed last year.

Read more: 45 journalists killed in 2021 around globe

He did give the source of the statistics. Unesco, the UN organisation that sponsors World Press Freedom Day, said earlier this year that 55 journalists and media workers were killed in 2021.

"A special thanks to those who, with courage, keep us informed about humanity's wounds," the pope said.

Last month, Francis honoured journalists killed covering the Russia-Ukraine war, saying he hoped God would reward them for serving the common good.

The New York-based Committee to Protect Journalists says it has confirmed that at least seven journalists have died while covering the war in Ukraine and is investigating whether others were killed because of their work.

Reporters Without Borders, which is based in Paris, says it has documented a number of attacks directly targeting journalists wearing "Press" armbands in Ukraine.