Mr Mitchell, who quit the Government last month after abusing police officers, is facing questions from MPs about decisions he took as International Development Secretary.
In September, hours before leaving the development department to become Conservative Chief Whip, he restored British aid to Rwanda, whose president Paul Kagame has faced allegations of human rights violations.
Mr Mitchell was instrumental to building close ties between the Conservative Party and Rwanda under Mr Kagame. He helped establish an annual trip to the country by Conservative members to help development projects there.
British aid to Rwanda was suspended in July amid allegations that Mr Kagame was supporting the M23 rebel group in the neighbouring Democratic Republic of Congo.
Critics including the Labour Party have questioned Mr Mitchell's decision to restore aid and authorise payments worth £16 million. MPs on the International Development Select Committee are now investigating the decision.
Mr Mitchell said that the decision had been taken in response to reports from the region suggesting that the Rwandan government's conduct had improved.
He denied taking a personal decision without consulting colleagues, telling MPs that David Cameron and other senior ministers had been aware of his decision and approved it.
He said: "The British government decided, not some rogue minister, what would be the best response."
Repeatedly describing the restoration of aid as "a British government decision," Mr Mitchell told the MPs that at the Department for International Development, he worked closely with Ed Llewellyn, Mr Cameron's chief of staff.
On the timing of his decision, Mr Mitchell said he was aware a week before he left DFID that he was to be appointed Chief Whip. He used the time in the department to "clear the decks" for his successor, Justine Greening.
Mr Mitchell said that continuing to withhold budget support for Rwanda would have little impact on the Rwandan leadership and other political elites.
However, it would "harm" ordinary Rwandans, he said, for instance by reducing the number of girls in school.
"If you withdraw budget support, you won't have an impact on the elite but you will degrade or damage important poverty relief programmes," he said.