The Congress of the People condemned on Tuesday in the "strongest terms" the "unruly behaviour" of the crowd at Freedom Day celebrations in Durban.

"It is completely unacceptable that a sitting president of the country was subjected to such undignified behaviour," said Cope president Terror Lekota in a statement.

"This proves that the separation of powers between State and party are blurred. Events of this nature are held to celebrate national unity and cohesion."

People threw objects and disrupted President Kgalema Motlanthe's speech at Freedom Day celebrations at Durban's Absa Stadium on Monday.

Motlanthe had to stop his speech while ANC provincial chairman Zweli Mkhize persuaded the crowd to listen to Motlanthe.

The disruptions began when people who were sitting high up in the stadium complained about the quality of the sound. Some continued singing despite Mkhize's call for calm.

"Cope condemns in the strongest terms the unruly behaviour...

"Cope calls on ANC president Jacob Zuma to distance himself from such behaviour and for the ANC to educate its members about the significance of national events," said Lekota.