(Reuters) - A suicide bomber walked up to policemen stationed outside the High Court in the Pakistani city of Lahore on Thursday and set off his explosives, killing 22 people, most of them police, officials said.
Here is a chronology of some of the worst bomb attacks since July 2007:
July 14, 2007 - Suicide car-bomber kills 24 paramilitary soldiers and wounds 29 in North Waziristan.
July 15 - Sixteen people, most of them paramilitary soldiers, are killed in ambush on patrol in Swat valley in North West Frontier Province (NWFP). Separately, suicide bomber targets police recruiting centre in Dera Ismail Khan in NWFP, killing 29.
July 17 - Suicide bomber kills 16 people outside court in Islamabad, where country’s suspended chief justice, Iftikhar Chaudhry, was due to speak.
July 19 - Three suicide attacks in a single day in three towns kill at least 52 people.
July 27 - Suicide bomb attack in restaurant near Islamabad’s Red Mosque kills 13 people, most of them policemen.
September 4 - Two suicide bombers kill 25 in Rawalpindi.
September 11 - Suicide bomber kills 16 people in northwest Dera Ismail Khan.
Sept 13 - At least 15 soldiers killed in suicide bombing in an army canteen near Islamabad.
October 19 - At least 139 people killed in suicide bomb attack on Benazir Bhutto’s motorcade as she is driven through Karachi after arriving home from eight years in self-exile. The attack is one of the deadliest in Pakistan’s history.
October 25 - Suspected suicide bomber kills 21 people, including 17 soldiers, in an attack on an army convoy in the northwestern Swat valley.
November 24 - Twin suicide car bomb attacks kill 15 people in Rawalpindi, on the eve of the return of former prime minister Nawaz Sharif from exile in Saudi Arabia.
December 17 - A suicide bomber kills 10 military recruits in the northwestern town of Kohat.
December 21 - A suicide bomber kills at least 41 people in a mosque in northwest Pakistan during Eid festival prayers.
December 27 - Bhutto is killed in a gun and bomb attack after a rally in Rawalpindi. At least 16 others are killed in the attack.
Dec 31 - Violence flares as angry supporters of Bhutto take to the streets. The death toll of people killed in riots reaches 47.
January 7, 2008 - Al Qaeda-linked militants in northwest Pakistan attack two offices of a government-sponsored peace movement and kill eight people.
Writing by Nagesh Narayana and David Cutler