PESHAWAR, Pakistan — A suicide bomber killed at least 42 people yesterday at a meeting called by tribal elders to deal with rising Taliban militancy in Pakistan’s volatile northwest, authorities said.

Dozens of others were wounded in the blast, the third in three days in North West Frontier Province, a rugged and lawless region where Pakistani security forces are waging an increasingly deadly fight against armed Taliban and Al Qaeda supporters.

The series of attacks, in which more than 80 have been killed, underscores the grave security and political challenges facing the country as the opposition parties that won last month’s elections grapple with the task of forming a new government.

Hundreds of leaders representing five local tribes had assembled yesterday morning on an open plain in the town of Darra Adamkhel, about 20 miles south of the city of Peshawar, to plot a strategy to combat militants in their area. Witnesses said that the gathering, known as a jirga, finished about 11 a.m. local time, with about 200 men staying behind to work out the details of a plan to establish a volunteer militia. About half an hour later, a suicide attacker blew himself up in their midst, authorities said.

Television footage showed shoes, caps, and blood scattered around the site of the blast. Local hospitals were overwhelmed with casualties, which officials yesterday night said included at least 42 dead and 53 injured.

Local residents identified the bomber as a teenager from Darra Adamkhel, a town known as a hotbed of illegal gun manufacturing. The bombing was the second major attack within days that managed to kill more than three dozen people at once. Friday, a suicide bomber struck at a school in the scenic Swat Valley where mourners had gathered for the funeral service of a high-ranking police officer.