The first round of Iran's presidential election revealed shrinking support for both reformists and conservatives, even though some voters are pushing for change by backing the sole reformist candidate, analysts say.

Masoud Pezeshkian, the reformist contender, and ultraconservative Saeed Jalili led the polls held on Friday to replace the late ultraconservative president Ebrahim Raisi, who died in a helicopter crash last month.

Friday's vote, marked by a historically low turnout, "clearly shows that both reformists' and conservatives' bases have considerably shrunk," said Ali Vaez of the International Crisis Group think tank.