The son of former Pakistani Prime Minister Benazir Bhutto has made his political debut at a huge rally on the fifth anniversary of his mother’s death.

24-year old Bilawal Bhutto Zardari called himself “the heir to the martyr”, as he addressed a crowd of hundreds of thousands in Pakistan’s southern province of Sindh.

He was flanked by his father, Asif Zardari, Pakistan’s current president. Zardari, elected after his wife’s death, does not enjoy her level of popularity. He is currently locked in a power struggle with Pakistan’s Supreme Court, which is keen to re-open corruption cases against him.

The young Bhutto is already co-chair of Pakistan’s People’s Party, although he cannot run in spring’s presidential election as candidates must be over 25.

Benazir Bhutto’s killer has never been caught and her son used his speech to denounce the slow pace of the investigation into her death.