A suspected truck bomb has ripped through the heart of Kabul's diplomatic district, killing at least 80 people and wounding hundreds, in a powerful blast described by officials as "one of the biggest" to have hit the Afghan capital.

Sources said Wednesday's suicide attack took place near Zanbaq square, in Kabul's 10th district, close to shops and restaurants, as well as government offices and foreign embassies.

There was no immediate claim of responsibility. Zabihullah Mujahid, a spokesman for the Taliban, told Al Jazeera that the group was not involved in the attack.

Police and health officials confirmed to Al Jazeera that at least 80 people were killed and more than 300 wounded in the attack. The death toll was expected to rise.

The victims appear mainly to have been Afghan civilians and there were no immediate reports of casualties among foreign embassy staff.

"The area is heavily guarded and there is usually traffic jam, just because of security-controlled points in the area," Mushtaq Rahim, an independent analyst and security commentator, told Al Jazeera from Kabul.

"And that was one of the main reasons that we had so many civilian casualties. because of the congestion that happens in that area."

Video shot at the scene showed burning debris, crumbled walls and buildings and destroyed cars, many with dead or wounded people inside.