At least 91 people have been killed after a huge car bomb ripped through a busy market in Peshawar, Pakistan.

巴基斯坦白沙瓦地区一辆自杀式爆炸汽车冲进繁忙的集市，造成至少91人丧生。

The attack, which injured at least 200 others, was the deadliest to hit Pakistan this year.

Similar attacks have killed hundreds of people in recent weeks, as the army carries out an operation against Taliban militants² in South Waziristan.

The blast came as US Secretary of State Hillary Clinton began a visit to the Pakistani capital, Islamabad.

Mrs Clinton told a news conference the US was "standing³ shoulder to shoulder" with Pakistan in its fight against "brutal⁴ extremist groups（极端主义团体）".

The Taliban have denied being behind this bombing, but the government blames them for a wave of attacks apparently⁵ launched in response to the army operation against their strongholds on the Afghan border.

The BBC's Syed Shoaib Hasan in Islamabad says that few people will take the Taliban's denial seriously and they remain the major suspects for the bombing - if only because few other groups would have a motive⁶ for carrying out such a devastating⁷（灾难性的，破坏性的） attack.

The blast tore through buildings in Peshawar's Peepal Mandi market street, destroying several - including a mosque⁸（清真寺） - and leaving others on fire.

The market mostly sells products for women, and most of the dead were women and children.

"There was a huge blast. There was smoke and dust everywhere. I saw people dying and screaming on the road," eyewitness⁹ Mohammad Siddique told AFP news agency.

Crowds dug through rubble¹⁰ to rescue people.

'We will not buckle¹¹'

Medical staff appealed for people in Peshawar to give blood.

Some complained that the authorities were not prepared to deal with the aftermath of such a large attack.

"There were a lot of wounded people. We tried to help them but there were no ambulances so we took the victims on rickshaws（黄包车，人力车） and other vehicles," Muzamil Hussain told the Associated Press.

"There were no police. The police and government didn't help us, the police even opened fire on us."

Security has been stepped up across Pakistan, but the government still appears to be unable to stop the attacks, the BBC's Mark Dummett in Islamabad says.

Foreign Minister Shah Mahmoud Qureshi promised that the country's resolve would not be shaken by "such heinous¹² crimes（滔天罪行）".

At a news conference in Islamabad with Mrs Clinton, he told potential militants: "We will not buckle, we will fight you. We will fight you because we want stability and peace in Pakistan."

'Brutal extremists'

Mrs Clinton is in Pakistan to discuss US concerns about the increasing numbers of militant¹ attacks and the security of the country's nuclear weapons.

She condemned¹³ the "vicious（恶毒的，凶残的） and brutal" attack in Peshawar and said the fight against the Taliban was "not Pakistan's alone".

"Pakistan is in the midst of an ongoing¹⁴ struggle against tenacious¹⁵（固执的，不屈不挠的） and brutal extremist groups who kill innocent people and terrorise communities," she said.

"We commit to stand shoulder to shoulder with the Pakistani people in your fight for peace and security, we will give you the help that you need in order to achieve your goal."

Last week, Pakistan launched an offensive in South Waziristan, which is considered to be the main sanctuary¹⁶（圣所） for Islamic militants outside Afghanistan.

Correspondents say the Peshawar blasts will come as a violent reminder¹⁷ for the US of the difficult task it is facing in the fight against the Taliban, both in Pakistan and across the border in Afghanistan.