Pope Francis on Monday blamed accidents at work on excessive profit-seeking and the "idolatry of the market," in a fresh swipe at unbridled capitalism that has led some right-wing critics to paint him as a far-left radical.

His remarks came two weeks after five railway maintenance workers were killed by a passing train in the northern Italian town of Brandizzo. The accident has been linked to a suspected breach of health and safety regulations. 

"Tragedies (in the workplace) begin when the focus is no longer on man, but on productivity, and man turns into a production machine," Francis said in a speech to the Italian association of people injured at work.

He said he was still thinking about the five men killed in Brandizzo.

Francis likened the frequent reports of workplace tragedies to a "war bulletin". Such incidents happen when "work becomes dehumanised ... and turns into an exasperated race for profit," he said. 

The pope lashed out at "carewashing", by businesspeople and politicians who "instead of investing in safety (at work), prefer to wash their consciences with some charitable work," donating to the arts or sports.

"Responsibility towards workers is a priority: life cannot be traded for any reason, especially if it is (the life of the) poor, precarious and fragile. We are human beings and not machines, unique people and not spare parts," he said.

Soon after he was elected in 2013, Francis said he wanted to lead a "poor Church, for the poor" and has reiterated several times that worrying about the needy was not a form of communism, but a tenet of the Gospel.