Senol Simsek, a witness who provided first aid to the wounded, told the NTV television network that he had seen at least five people lying and writhing near a telephone booth that was destroyed.

The police quickly sealed off the entire area and closed it to all traffic.

Hayati Yazici, deputy prime minister who happened to be visiting Istanbul on Sunday, visited the bombing site and told the Anatolian News Agency: “It is obvious that this is the work of a villain organisation, a person or people, however it is not certain as to who this is. Our friends are investigating, it will be discovered for sure.”

The double bombing appeared to be the most serious terrorist attack here since twin truck bombings at two Istanbul synagogues killed 23 people on November 15, 2003.