BERLIN (AFP) - The Berlin Philharmonic, regarded as one of the world's best orchestras, said Tuesday that 43-year-old Russian Kirill Petrenko would take up his new position as chief conductor in 2019.

At the same time, Petrenko - whose nomination in Berlin in June took the classical music world by surprise - has extended his contract as general music director (GMD) at the Bavarian State Opera in Munich until 2021, the opera house announced separately.

In Berlin, Petrenko is taking over from Britain's Sir Simon Rattle, who is stepping down in 2018 after 16 years in the post.

"Kirill Petrenko will assume his new position as chief conductor and artistic director of the Berlin Philharmonic starting with the 2019/2020 season," the Berlin Philharmonic said in a statement.

"Out of consideration for his commitments at the Bavarian State Opera in Munich, he will conduct a reduced number of concerts in his first season as chief conductor in Berlin."

But Petrenko would appear on the podium with the orchestra as guest conductor in the 2016/2017 and 2017/2018 seasons, the statement added.

And in 2018/2019, he would also conduct a number of concerts and take the orchestra on tour.

At the same time, the Bavarian State Opera, where Petrenko has been GMD since 2013, said the notoriously media-shy and self-effacing conductor had agreed to extend his contract at the house until 2021, meaning there would be an overlap of two years between the two appointments.

The combined workload of the two positions is very heavy.

"Due to Maestro Petrenko's commitment as chief conductor of the Berlin Philharmonic, in his final season of 2020/21 he will be working at Bavarian State Opera as a guest conductor," the opera house said.

Petrenko said: "I feel very dedicated to the Bavarian State Opera, its orchestra and not least of all to Munich's wonderful public."

"For me, personally, it is important to work... in this house and with this orchestra."

The Berlin Philharmonic is unique in the world of classical music in that it chooses its chief conductor itself.

After initially failing to agree on Rattle's successor back in May, the orchestra's 124 musicians picked Petrenko in June "by a big majority".