Kabul: A suicide bomber blew himself up near a Shiite shrine in Kabul on Wednesday, killing at least 29 people and wounding dozens, officials said, as the Afghan capital celebrated the Nawruz holiday marking the start of the Persian new year.

The explosion underlined the threat to the city from militant attacks, despite government promises to tighten security in the wake of an attack in January that killed around 100 people.

Militant group Islamic State, which has claimed several previous attacks on Shi'ite targets, claimed responsibility, its Amaq news agency said. The Taliban issued a statement denying any connection.

Kabul had been on alert for attacks over the Nawruz holiday but the bomber was still able to detonate his explosives as people were leaving the Kart-e Sakhi shrine, in a heavily Shi'ite area in the west of the city.

"When the explosion took place, I fell to the ground and I saw many people on the ground around me," said Ramazan, who was wounded in the blast at the shrine, near the city's main university.