Polish voters have elected their first openly gay mayor as the heavily Catholic country gradually shifts its stance on gay rights.

Robert Biedron won a runoff election over the weeked with 57 percent of the vote in the northern city of Slupsk, the local election commission said.

The 38-year-old member of the small leftist Your Move party ran as an independent against a candidate from the governing centrist Civic Platform party.

The political scientist was elected the EU member's first openly gay member of parliament in 2011 -- the same year that Poles voted in their first transsexual lawmaker, Anna Grodzka.

Poland is one of Europe's most devout countries. Ninety percent of residents identify themselves as Roman Catholic, though fewer and fewer are heading for the pews on Sunday.

"When you really want something, you can move mountains," Biedron told reporters after his win.

The gay rights activist campaigned on the slogan "Change, finally". His programme notably featured city-wide free Internet access and an emphasis on energy efficiency.

Biedron, who said he will be riding his bicycle to work, was listed this year by the Polityka weekly as one of Poland's 10 best lawmakers.

mc-via-amj/mas/ccr