The official, who insisted on anonymity, said that Abdul Jabbar, a Briton killed in a strike near Pakistan’s border with Afghanistan on Sept. 8, “had some links to Faisal Shahzad, but the nature of the ties are not clear.”

On Tuesday, after Mr. Shahzad was sentenced to life in prison by a judge in New York, the BBC reported that an unnamed “very senior Pakistani security source” said that Mr. Jabbar was at the center of a plot to launch commando attacks in Britain, France and Germany, modeled on the one in Mumbai, India, in 2008.

According to the source, who spoke to BBC’s Newsnight, Mr. Jabbar, a married British citizen living in Pakistan’s Punjab Province, was supposed to establish a cell in Britain and lead the attacks. The BBC added, “Intelligence agencies monitored a meeting of 300 militants three months ago in the Ambarshaga area of North Waziristan, attended by Jabbar and militants from the Taliban and Al Qaeda.”