Police in Kazakhstan have arrested hundreds of people protesting against a poll to elect the country's first new president in 30 years, the BBC reports.

The election was called after long-time leader, 78-year-old Nursultan Nazarbayev, stepped down in March.

His hand-picked successor, interim President Kassym Jomart-Tokayev, is widely expected to win the vote.

Protesters claimed the poll was not free and fair. But Tokayev described the process as democratic and open.

Exit polls suggest 66-year-old Tokayev, a former director-general of the United Nations Office in Geneva, won the election with 70% of the vote.

Large-scale protests - the biggest the country has seen in years - have been reported in Kazakhstan's capital, Nur-Sultan, and its largest city Almaty.

Hundreds of peaceful demonstrators, and several journalists and activists monitoring them, were detained by police.