Conservative newcomer Andrzej Duda from the Law and Justice (PiS) opposition party won Poland's presidential run-off with 51.55 percent of the vote, official results showed Monday.

The 43-year-old lawyer and MEP's shock victory spells a possible return to power of the eurosceptic PiS -- and its leader Jaroslaw Kaczynski -- in the autumn parliamentary election. Rival liberals Civic Platform (PO) have governed the Central European heavyweight since 2007.