KANDAHAR, Afghanistan — A Taliban insurgent freed in exchange for a kidnapped Italian journalist will replace his slain brother as the militia's top field commander, a spokesman said Friday -- although Afghan intelligence insisted the new man had been killed.

Dadullah Mansoor was named to succeed his brother, Mullah Dadullah, a one-legged militant who orchestrated Taliban suicide attacks and beheadings and who was killed last weekend in a U.S.-led operation in southern Afghanistan.

Purported Taliban spokesman Shuhab Athul said Mansoor was one of the five prisoners released in March in exchange for Italian journalist Daniele Mastrogiacomo.

"Mullah Dadullah's death will not deter the Taliban's summer activities,'' Athul said by telephone. "The Taliban will increase its activities against the government and occupying forces.''

He reiterated a Taliban demand that the government release Dadullah's body to his relatives, saying if they do not, "the consequences will be very bad.''

The Afghan intelligence service said Wednesday that three Taliban prisoners exchanged for Mastrogiacomo were killed alongside Dadullah. It said Dadullah's brother, whom they identified as Mullah Shah Mansoor, was among those killed.

However, Athul said that the Mansoor who was killed was one of Dadullah's minor commanders -- not his brother.

"His brother, Dadullah Mansoor, is alive, and he is replacing Dadullah,'' Athul said.

Sayed Ansari, spokesman for the intelligence service, said Friday that the agency stood by its findings.

"Our statement is correct,'' Ansari said. "We don't know about what they (the Taliban) are saying.''