Ten people were killed during street protests in Iran on Monday, Iran's state television said on Monday.

The nationwide protests have drawn in tens of thousands of people and represent the boldest challenge to Iran’s leadership since pro-reform unrest in 2009. Calls for more demonstrations on Monday raise the possibility of prolonged instability.

"In the events of last night, unfortunately, a total of about 10 people were killed in several cities," the state television said while showing footage of damage from the demonstrations.

Unsigned statements posted on social media urged Iranians to demonstrate again in the capital Tehran and 50 other urban centers.

The unrest erupted in the second city of Mashhad against price rises but it swiftly spread and turned into political rallies.