ANKARA (Reuters) - Turkish police foiled a bomb attack in Ankara on Tuesday, the sixth anniversary of 9/11 attacks on the United States, averting what officials said would have been a disaster for the capital.

Turkish police officers stand guard as a van packed with explosives is transferred on a police vehicle from a multi-storey car park after it was found by police in Ankara, September 11, 2007. REUTERS/Anatolian

Ankara governor Kemal Onal said police had found a vehicle packed with explosives in a multi-storey car park in a central district of the city of four million. Shops and offices in the area were quickly evacuated.

“The police efforts prevented a possible disaster ... It is too early to say who was behind this but the bomb was big and I do not want to think what might have happened if it had gone off,” Onal told reporters.

Private broadcaster NTV said police had found about 300 kg of explosives in the vehicle, a stolen mini-bus parked on the second floor of the car park.

The state Anatolian news agency said it took experts three hours to defuse the bomb.

Kurdish separatists, ultra-leftists and Islamist militants have all carried out attacks in Turkey in recent years.

CNN Turk quoted police as saying the device found resembled those used in al Qaeda-backed suicide bomb attacks in November 2003 on two synagogues, the British Consulate and the HSBC bank in Istanbul. More than 60 people died in those attacks.

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But the governor’s office later said the explosives found seemed to point towards the involvement of Kurdish separatist rebels of the outlawed Kurdistan Workers Party (PKK).

Turkish authorities have also blamed the PKK for a suicide bombing at a central Ankara shopping centre in May that killed at least six people and injured dozens. The PKK denied any involvement in that attack.

PANIC

Police threw a wide cordon around the car park on Tuesday after identifying a suspicious-looking minibus.

“Police ordered us to evacuate our building. People panicked and started running,” said Abbas Yuksel, 38, who works for a construction company based in the area.

Onal noted that September 11 and 12 were particularly sensitive days. The world remembers on Tuesday al Qaeda attacks on New York and Washington, while Turkey will mark the anniversary of its 1980 military coup on Wednesday -- a possible focus for leftist groups.

A U.S. air base in western Germany received a bomb threat on Monday evening, prompting a large operation by local police and American forces to secure the site, police said on Tuesday.

The base received a call from a man who spoke in German with a Russian or Turkish accent and threatened to attack the air base in Spangdahlem with bombs.

Al Qaeda leader Osama bin Laden released a tape on Tuesday praising one of the hijackers involved in the Sept 11, 2001, attacks on New York and Washington.

Bin Laden made a passing reference in his address to Ankara, but only to mention a historic event. He made no comment on the policies of modern Turkey, a Muslim but secular state and NATO member whose close links to the West make it a potential target for militant Islamists.