DHAKA: The only son of Benazir Bhutto, Pakistan's assassinated former prime minister, has told tens of thousands of supporters that he would fight for his party's revival in an appearance intended to mark the official launch of his political career.

"The fountainhead of our power is the people," Bilawal Bhutto Zardari, 26, told the crowds in the port city of Karachi, Pakistan's financial hub.

Bhutto is tipped to become, main opposition group, the Pakistan People Party's (PPP) next leader.

Police said 150,000 people gathered to hear the young leader speak. Security was tight during the rally, where crowds of supporters sang and danced, waving party flags.

"If you want to save Pakistan, the only answer is Bhuttoism and the PPP," Bhutto said.

In his two-hour speech, delivered in Urdu, Bilawal condemned the homegrown Pakistani Taliban and other similar groups including the Islamic State of Iraq and the Levant, which controls large swathes of Iraq and Syria.

BDST: 1240 HRS, OCT 19, 2014