The lives of more than four million children can be saved by a set of vaccines which cost the same as a cup of coffee, International Development Secretary Andrew Mitchell has said ahead of a major conference.

Speaking before today’s Global Alliance for Vaccines and Immunisation (Gavi) conference in London, the Sutton Coldfield MP said it was right Britain played a leading role in protecting the world’s poorest children.

Mr Mitchell also defended Britain’s aid budget, which despite cuts across Whitehall has increased, prompting vocal criticism from the Tory backbenches.

He said it was not only “morally right” but in the UK’s national interests to continue to fund development projects around the world.

His comments came as the Prime Minister David Cameron said it would be wrong to “turn inwards solely to our own problems and effectively balance our books while breaking our promises to the world’s poorest”.

Speaking on BBC’s Andrew Marr Show, Mr Mitchell said Britain would show leadership at the conference, where the Prime Minister is expected to pledge an increase in Britain’s contribution to Gavi.

He said: “We had a look when we came into Government at all the different ways that Britain does development with British taxpayer funds and one of the very best was the Global Alliance of Vaccines and Immunisation, where effectively you can vaccinate a kid in the poor world for the price of a cup of coffee against all five of the killer diseases which mean so many of these children die before the age of five.

“Children in Britain do not die from these diseases so everyone is coming together tomorrow for a pledging conference to support this, led by our Prime Minister.

“We are hoping by tomorrow lunch time to have raised sufficient funding over the next four years to vaccinate 250,000 children in the poor world and save millions of lives.

“It’s really important. It’s Britain’s big ask for development this year. We want to support it very strongly. We have a leadership role in all of this and as a result of the action that will be taken tomorrow, we have a real chance of saving more than four million children’s lives.”