SAIDU SHARIF, Pakistan — A renewed wave of violence struck Saturday in small-town Pakistan when a suicide bomber on a motorized rickshaw killed 13 people at a security checkpoint, raising fears the nation is sliding back into a period of relentless bloodletting.

The blast -- the second major attack in Pakistan in less than 24 hours -- occurred in the Swat Valley, where Taliban fighters battled government soldiers for months last year.

The attack in Saidu Sharif, Swat's administrative capital, also wounded 52 people. A day earlier, two suicide bombers killed 55 people in co-ordinated explosions in the eastern city of Lahore.

No one has claimed responsibility for either attack, but suspicion quickly fell on the loose network of Islamist insurgents who have been fighting the U.S.-allied Islamabad government and who have stepped up attacks against security forces in recent days.

Maj. Gen. Ashfaq Nadeem, a top military official for the region, said the dead in Saturday's attack included two soldiers and two policemen.

"Such acts cannot demoralize us. I want to assure the people of Swat that we will continue fighting till the last Taliban are eliminated," he said.

The bomber, driving a three-wheeled motorized rickshaw, targeted a roadblock manned by soldiers and police. The explosion sparked panic in the neighbourhood, as soldiers in battle gear carried victims -- injured and dead -- through the narrow bloody streets to get them help.

Speaking from his hospital bed, Zia-ur-Rehman said he was travelling in another rickshaw when the blast shook the street and violently jolted his vehicle.

"I thought somebody picked me up and then threw me down," said the 24-year-old, who was covered with cuts and bruises. "Everybody was crying."

The Pakistani military launched a major offensive in Swat early last year after the collapse of peace talks with local Taliban, who at the time controlled much of the valley.

The military took back control of the valley by mid-2009, but sporadic violence has continued.

In Lahore, meanwhile, funerals were being held Saturday for the dozens of people killed the day before.

Police official Chaudhry Shafiq said the death toll from that attack rose to 55 Saturday after 12 more people died overnight. About 100 people were wounded.

That attack occurred when two suicide bombers set off their explosives within seconds of each other near two trucks carrying soldiers on patrol in RA Bazaar, a residential and commercial neighbourhood with numerous military buildings. About 10 of those killed were soldiers, said police Chief Parvaiz Rathore.

The militants have been fighting to destabilize the Islamabad government. They launched a bloody wave of bombings last fall across Pakistan, leaving 600 people dead in near-daily attacks in apparent retaliation for an army offensive against the insurgents' main stronghold, in the tribal region of South Waziristan along the Afghan border.

While the insurgent attacks had slowed early this year, they have risen sharply in recent days, a clear sign that the militant network has not been broken -- despite a string of recent arrests, regular U.S. missile attacks and last year's offensive.

While it is unclear why the attacks have increased, their toll is obvious: At least 88 people have been killed in the recent wave of bombings.