A video grab from footage broadcast by the UK Parliament's Parliamentary Recording Unit (PRU) shows attends at a Parliamentary Privileges Committee hearing, in central London on March 22, 2023. (Photo: AFP)

A British parliamentary committee on Wednesday opened an inquisition into former prime minister Boris Johnson to determine whether he told the truth about the "Partygate" scandal.

Harriet Harman, the Labour opposition chair of the privileges committee, said the MPs wanted to establish whether he "told the truth to the best of his knowledge", arguing the answers went to the "heart of our democracy".