Two people have been killed and at least five wounded in an explosion in the Turkish city of Istanbul.The cause of the explosion is not known but one report said it occurred in a rubbish bin. Turkey has been hit by several bombings in recent weeks. On Tuesday two bombs exploded in rubbish bins in the southern resort town of Anatalia, wounding six people. And last month a bomb exploded on a tourist bus in the popular resort of Kusadasi, killing five people and wounding 13 others. Kurdish rebels from the banned Kurdistan Workers Party have been blamed for the most recent attacks. Islamic extremists have also been active in the past.