Poland's government plans to jail paedophiles for longer after a powerful new documentary about abuse among priests went viral.

“Tell No One", by independent journalist Tomasz Sekielski, has been viewed more than 15 million times since it was posted to YouTube on Saturday.

The Law and Justice (PiS) government, which is closely allied with Poland's Catholic church, said parliament would debate the proposed changes within days.

The announcement came ahead of a tight race in elections to the European Parliament.

'Deeply moved'

"Paedophilia has been treated too lightly by our judicial system," Prime Minister Mateusz Morawiecki told reporters on Tuesday.

The sentence for rape of a child, which is currently up to 15 years in prison, would be increased to 30 years if the plans are passed by Parliament.

“Tell No One” shows the meeting of victims of paedophile priests with their abusers and challenges the church hierarchy for its weakness — and sometimes absence — of sanctions.

"I am deeply moved by what I saw in Tomasz Sekielski's film, and I apologize for all the wounds inflicted by the men of the Church," the Polish primate Archbishop Tomasz Polak said in a statement.