At least 30 people have been killed and dozens injured in a suicide bombing on a Shia Muslim march in the Pakistani city of Karachi, officials say.

巴基斯坦城市卡拉奇发生自杀式炸弹袭击什叶派穆斯林事件，至少30人丧生、数十人受伤。

The attacker had been walking amidst a procession队伍，行列 with tens of thousands of people, said the interior minister内政部长.

After the explosion, marchers turned their anger on ambulance workers, security forces and journalists.

Pakistan's security forces have been on high alert as Shia什叶派 Muslims marked the holy month of Muharram伊斯兰教历的第一个月.

Ashura on Monday was the climax¹高潮，顶点 of the holy period, commemorating² the death of the Prophet穆罕默德，先知 Muhammad's grandson.

Blood-stained walls

There was no immediate³ claim of responsibility for the attack, which comes amid an upsurge高潮，高涨 of violence by Taliban militants⁴ in Pakistan.

Karachi has a long history of sectarian宗派的 violence between Shias and Sunnis逊尼派.

There have been numerous attacks on such processions across the country over the last few days, says the BBC's Aleem Maqbool.

On Sunday, eight people were killed when a suicide bomber⁵ targeted a Shia march in Pakistan-administered Kashmir.

Interior Minister Rehman Malik blamed Monday's blast on extremists who wanted to destabilise Pakistan.

"Whoever has done this, he cannot be a Muslim. He is worse than an infidel无信仰者，异教徒," he told reporters.

Karachi police chief Waseem Ahmed said the severed⁶ head of the bomber had been found, reports Reuters news agency.

One survivor⁷, Naseem Raza, told AP news agency: "I saw walls stained with blood and splashed with human flesh. I saw bloodstained血污的，血腥的 people lying here and there."

Fleeing the scene of the blast, another mourner told AFP news agency: "My sister, her husband and children are dead."

The bombing unleashed⁸ further pandemonium一片混乱 as angry Shia mourners fired shots in the air.