* Moderate clerics often targeted by Boko Haram
* Islamists are spreading attacks across Nigeria
* Mass targeting of civilians surging (Updates toll, adds police commissioner, details, crowd reaction)
By Garba Muhammed
KADUNA, Nigeria, July 23 (Reuters) - Two bomb blasts in the north Nigerian city of Kaduna killed at least 82 people on Wednesday, officials said, in attacks that bore the hallmarks of violent Islamist group Boko Haram.
A suicide bomber targeting a moderate Muslim cleric killed at least 32 of the cleric's congregation on a busy commercial road. Shortly after, a second bomb blast killed 50 people in the crowded Kawo market on Wednesday, a local Red Cross worker on the scene, who declined to be named, told Reuters.
Thousands were gathered for prayers with Sheikh Dahiru Bauchi in Murtala Muhammed square, and when his convoy pulled up, the bomber lunged at him before being stopped by his private security, witnesses and police said.
"The attack was targeted at the sheikh. No arrest has been made yet," said police commissioner Shehu Umar.
The bomb did not injure Bauchi, several witnesses told Reuters. Mustafa Sani, a volunteer for Bauchi's mosque evacuating bodies, said there were 32 confirmed dead so far.
"Somebody with a bomb vest ... was blocked. He detonated the bomb along with the person that tried to block him," Umar said, adding that police had only been able to confirm 25 dead, with 14 wounded. Police sometimes give lower casualty tolls than workers on the scene.
A Reuters reporter saw blood and body parts scattered on the Alkali Road in the city centre. The military used pick-up trucks to cordon off the area. Sirens wailed as fire engines raced to the scene.
An angry crowd started throwing stones at police, who responded by dispersing them with tear gas. Some followers had come from Senegal, Chad and Niger to see the popular sheikh.
BOKO HARAM SUSPECTED
There was no immediate claim of responsibility for either blast, but Islamist militant group Boko Haram has been staging attacks, especially with explosives, outside its northeastern heartlands in the past three months.
Since launching an insurgency in 2009, the militants have often attacked clerics, like Bauchi, who take issue with their Salafist ideology. If Boko Haram is responsible for Wednesday's attack, it underscores the risks moderate clerics take speaking out against it.
The insurgents, who are fighting to carve out an Islamic state in Nigeria, have repeatedly targeted civilians this year, mostly in remote northeastern Borno state. They killed more than 2,000 civilians during the first half of this year, Human Rights Watch (HRW) estimated a week ago.
The Islamists sacked the northeast town of Damboa and surrounding villages over the weekend, killing at least 50 people.
The rebellion has been in the international spotlight since Boko Haram fighters kidnapped more than 200 girls from a school in the northeastern village of Chibok on April 14th. President Goodluck Jonathan met parents of the abducted girls, and some other girls who had escaped, for the first time on Tuesday.
Boko Haram leader Abubakar Shekau last week claimed responsibility for two explosions on June 25 at a fuel depot in Lagos, Nigeria's commercial hub, that killed at least two people.
A military offensive since May last year that was meant to dismantle their hold on the northeast has caused the militants to react in two ways: brutal attacks on civilians in the region have surged dramatically, and efforts to strike out in areas far from the rebels' strongholds have resumed.
A blast in the central city of Jos, 170 km (105 miles) east of Kaduna, killed 118 people in May. (Writing and additional reporting by Tim Cocks; Editing by Andrew Heavens and Sonya Hepinstall)