ANKARA, May 22 (RIA Novosti) - The mayor of the Turkish capital, Ankara, said four people were killed and 56 injured in a powerful explosion in the city center Tuesday.

Melih Gokcek said in televised remarks that the blast outside a shopping mall in central Ankara had most likely been caused by a bomb.

The local NTV broadcaster quoted police sources as saying the explosion was the result of a suicide bomb attack staged by Kurdish separatists.

Militants of the Kurdistan Workers Party have been blamed for a series of bomb attacks on tourist sites in Turkey last year, which killed more than a dozen people.