Poland's prime minister says Pope Francis, who is due to visit the country in July, has praised her policy supporting large families.

Prime Minister Beata Szydlo, a Catholic and the mother of a priest, met with Francis at the Vatican on Friday.

Her government is introducing sweeping changes to state offices and social policy, including giving extra financial support for parents with many children.

Szydlo says Francis is "glad that Poland has a program supporting families."

Szydlo told TVN24 after the meeting with the pontiff that everyone hopes Francis' July 27-31 visit is "safe and fruitful."

Security officials in Poland have warned that a major site for Francis' meeting with world youth, a vast meadow near the southern city of Krakow, could be difficult to secure.