Kiev, Feb 23 (IANS): At least two people were killed and nine others injured in an explosion during a march in the eastern Ukrainian city of Kharkov Sunday afternoon, local health department said.

The blast happened during a peaceful march to mark the first anniversary of the regime change, Xinhua news agency reported.

One policeman and a civilian were killed in the blast, and those wounded have been hospitalised, three of whom were in "serious condition".

Kharkov regional police chief Anatoly Dmitriyev termed the explosion as "terrorist attack".

The Security Service of Ukraine (SSU) detained four suspects in connection with the explosion, and weapons were found with them, including a grenade launcher.

"According to preliminary reports, a bomb filled with shrapnel was set off in Kharkov. The bomb was placed in a plastic bag. It was hidden under the snow at the roadside," the Interfax news agency quoted Kharkov regional prosecutor Yuriy Danylchenko as saying.

Earlier reports quoted the witnesses as saying that the explosion was caused by an explosive device thrown from a passing car into the rally crowd.

Alexander Pivovar, head of Kharkov regional department of SSU, said the bomb "was similar to that used in the powerful explosion near the Moskovsky Court" also in the city of Kharkov Jan19, which wounded 13 people.