Pictured: The moment two bombs killed 17 and injured 150 in busy Istanbul shopping district

The image was captured by a person using a mobile phone to film the horrified reaction to the first, smaller bomb.

Television showed ambulances carrying badly wounded victims to hospital after the explosions in the working class Gungoren district.

'It is certain this is a terror attack,' city governor Muammer Guler told reporters.

Terror: Caught on a mobile phone, the second of two bombs exploding in Istanbul

An injured woman and a child are taken into an ambulance after an explosion which has killed at least 15 people in Istanbul

The blasts, in a busy square, involved two blasts apparently intended to cause the maximum number of casualties.

The first, a small explosion in a telephone kiosk, caused only a few casualties. But a far bigger bomb, hidden in a garbage container, went off ten minutes later, blasting the crowds who had come to help the first victims.

One witness said: 'Tens of people were scattered around.'

The square is a popular meeting place because it is closed to traffic.

Huseyin Senturk, who owns a shoe shop nearby, said: 'The first explosion was not very strong. Several people came to see what was going on. That's when the second explosion occurred and it injured many onlookers.'

Abdullah Toker, a manager at Gungoren Kolon Hospital, said: 'We received nearly 30 very heavily wounded people.

Governor Guler called it a 'heinous attack'.

He said: 'The blasts occurred in a very busy district and this raised the casualties.'

Several groups, including Kurdish separatists, far-left groups and Islamists, have carried out bomb attacks in Istanbul in the past. Turkish TV, citing security sources, said police suspect Kurdish rebels may be responsible for the latest blasts. 

It said intelligence reports had suggested they were planning a bombing campaign.

People injured during one of the two bomb blasts wait for help from emergency services

Turkey has been plunged into political uncertainty by a court case over banning the ruling party which begins today.

The Constitutional Court will deliberate on whether the AK Party has engaged in Islamist activities and should be closed under Turkey's constitution, which draws a clear divide between religion and state.

The court can find the AK Party not guilty and dismiss the case, or convict it and either fine or ban the party and some of its leaders.

If that happens the government will fall and early parliamentary elections be called, possibly in November.

The case has entrenched the struggle between a government which, though rooted in political Islam, denies the charge of trying to introduce Islamic rule, and an establishment which sees itself as the guardian of secularism.

Forensic officers investigate the scene of the two bomb explosions in a busy shopping district which left at least 15 dead

In Spain, police said they have have foiled a Basque terror plot to bomb holiday resorts.

Investigators say the leader of an ETA cell smashed last week was planning strikes in the Costa del Sol, an area popular with British holidaymakers.

Officers found maps and plans of resorts in a series of raids which led to the arrest of Basque separatist Arkaitz Goikoetxea and eight other ETA members in Bilbao in northern Spain.

The terrorists were planning attacks in shopping centres and hotels in Andalusia, court documents revealed yesterday. ETA regularly targets tourists in its campaign for Basque independence.