Czechs are casting ballots for a second day in the presidential runoff, with the former head of the Academy of Sciences challenging the pro-Russian incumbent.

President Milos Zeman and Jiri Drahos advanced to the second round of voting after none of the nine candidates seeking the largely ceremonial post received a majority in the first round two weeks ago.

Zeman, 73, is favored to win another five-year term but polls suggest a tight race in the ballot that ends Saturday.

Since he was elected in 2013, Zeman has divided the nation with his pro-Russian stance and support for closer ties with China. The former left-leaning prime minister has become known for his strong anti-migrant and anti-Muslim rhetoric.

Drahos, 68, a political newcomer, is seen as more Western-oriented.