The Afghan Intelligence Office could have been the primary target for the bomb explosion in Kabul today. Early reports say 24 people have been killed and many injured.

The explosion rocked central Kabul early on Tuesday and photos have emerged showing a thick plume of black smoke rising from the vicinity of the sprawling US embassy in the Afghan capital, Reuters witnesses said.

The US embassy and NATO headquarters said they were not affected by the blast.

Gunshots were heard in the area where the explosion happened, local witnesses reported.

The powerful explosion came during the morning rush hour, a week after the Taliban announced the start of its annual spring offensive.

A Reuters witness near the scene also reported hearing gunfire more than half an hour after the blast. Kabul police also reported some gunfire immediately after the blast.

Several major Afghan security agencies are based in the area, including the national directorate of security. The ministry of defence and the presidential palace are also within a few hundred metres.

Warning sirens blared out from the US embassy compound, which is also close to the headquarters of the main Nato-led mission in Afghanistan. There was no indication of the source of the blast, but rocket attacks remain relatively common in the city.

The US embassy said it was not affected by the blast. The Nato military coalition also said it was unaffected.

The blast rattled windows several miles away and sent a plume of thick smoke rising in the sky.

No group immediately claimed responsibility for the attack, but the Afghan Taliban last Tuesday announced the start of its so-called spring offensive, even as the government in Kabul seeks to bring the insurgents back to the negotiating table to end their drawn-out conflict.

The Taliban warned it would "employ large-scale attacks on enemy positions across the country" during the offensive, dubbed Operation Omari in honour of the movement's late founder Mullah Omar, whose death was announced last year.

The annual spring offensive normally marks the start of the fighting season, though this winter the lull was shorter and the Taliban continued to battle government forces, albeit with less intensity.


Pic: Plumes of smoke rise from the city centre of Kabul where the explosion took place.  The picture was tweeted by ‏‏@mogtabajawady1