The Hallé has appointed a new principal guest conductor and new assistant conductor.

As the Manchester orchestra celebrates its 150th birthday, Markus Stenz, music director of the city of Cologne, joins as second principal guest conductor and Polish-born Ewa Strusinska as assistant conductor.

Stenz is currently principal conductor of Cologne Opera and the Gürzenich Orchestra and former artistic director of the Melbourne Symphony Orchestra and principal conductor of the London Sinfonietta. He will conduct at least three weeks annually from 2009, along with involvement in major projects.

Mark Elder, the Hallé's music director, said of the appointment, "I am absolutely delighted to welcome Markus to the Hallé family. Having known and respected his work for many years, I believe the imagination and commitment he brings to his work will greatly benefit this magnificent orchestra and its public and enhance its international reputation."

Romanian Cristian Mandeal has served as first principal guest conductor since 2005 and will continue to play an important role.

Royal Northern College of Music junior fellow Strusinska succeeds Rory Macdonald at the end of his 30-month tenure as assistant conductor in September this year. Strusinska will hold the post for two years.

Established in 1858 by pianist and conductor Sir Charles Hallé, the Hallé is considered Britain's longest-established symphony orchestra.