At least eight people were killed and 28 injured after a bomb ripped through Pakistan's Lahore Thursday, officials said, the tenth attack in just under a fortnight pointing to a resurgence in Islamist violence.

The blast, the second to hit the provincial capital this month, crumpled cars and sent panic rippling through the city after a wave of attacks across Pakistan killed more than 130 people.

"My God, my God, I saw so many bodies," said Imtiaz Ali, a barber in a Toni&Guy hair salon opposite the blast site in the posh Defence Housing Authority suburb of the city, replete with upscale boutiques and cafes.

The building where the bomb went off was under construction in a market crowded with people, including children, the 34-year-old told AFP.

"When I came out I first just saw smoke and dust... Bikes upturned. Cars destroyed. My own colleague's car windows blown out. My clients' cars blown out. I was close to fainting."

Police and administration officials confirmed it was a bomb attack, as the provincial health minister Khawaja Salman Rafique and rescuers supplied the casualty toll.

"Four people died on the spot while another four died of their wounds in the hospital," Rafique said.

No group has yet claimed responsibility.

Just over an hour later rumours of a second blast in another affluent area nearby sent ambulances racing to the scene, though authorities later said the reports were false.

Panic also spread on social media as citizens exchanged messages purporting to be warnings from intelligence agencies, including one that falsely stated a general curfew had been ordered in Lahore with shoot-on-sight orders.

The rumours underscored growing nervousness across the country as a series of assaults shook Pakistanis emboldened by what had been a prolonged lull in violence.

The attacks included a previous bomb in Lahore on February 13 which killed 14 people, and a devastating suicide blast at a Sufi shrine in Sindh province that left 90 devotees dead.

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The incidents, most of which were claimed by the Islamic State group or the Pakistani Taliban, have dented optimism after the country appeared to be making strong gains in its decade-and-a-half long war on militancy.

"After some relief over the last year or two, it's turmoil again, it's very troublesome," Asha'ar Rehman, the Lahore editor of leading daily Dawn told AFP.

- 'Baiting' militants -

Islamabad launched a crackdown in the wake of the attacks, saying it has killed dozens of "terrorists" in recent days and carried out airstrikes on militant hideouts along the Afghan border.

Pakistan's Prime Minister Nawaz Sharif, who is in Turkey on a three-day visit, Thursday told reporters in Ankara that the recent wave of terrorism will not deter his government's resolve.

"Soon we will overcome it. It has further strengthened our resolve that we will not rest until complete eradication of terrorism," Sharif said.

On Wednesday the military announced a nationwide anti-terrorist operation, which defence analyst and retired general Talat Masood told AFP would "target sanctuaries... of militants in Punjab province and restrict their movements".

Pakistan had vowed to hold the final of its hugely popular Pakistan Super League in Lahore next month despite the surge in violence, promising "head of state level" security for foreign players taking part.

Rehman said such vows may have amounted to "baiting" militants.

"There are so many who feel that it invites the wrath of militants unnecessarily," he said.

The city, Pakistan's second largest metropolis, was also the scene of an attack on the Sri Lankan cricket team bus in 2009. Pakistan has not hosted high-level visiting teams since then.

Much of the uptick in security across the country over the past two years has been credited to an earlier military operation targeting militants in the tribal areas along the border with Afghanistan.

Pakistan has accused Afghanistan of harbouring the militants who have carried out the most recent attacks. Kabul and Islamabad routinely accuse one another of giving militants safe haven.