An exit poll shows that the liberal Warsaw mayor, Rafal Trzaskowski, and a conservative historian, Karol Nawrocki, are the front-runners in a presidential election in Poland on Sunday.

Warsaw's liberal mayor Rafal Trzaskowski won a narrow victory in Poland's presidential election, according to an exit poll, but a second-round run-off with conservative historian Karol Nawrocki will be required in two weeks' time to decide the country's next president.

Rafal Trzaskowski, the Warsaw mayor, appeared to have won the first round of the election. Prime Minister Donald Tusk is hoping his eventual victory will help push through a liberal agenda.