Millions of pounds donated to the Christian charity World Vision were secretly diverted to the Islamist group Hamas, including £60,000 from the UK that went to building a base for militants, Israel said on Thursday.

Israeli investigators arrested an alleged Hamas operative who they said infiltrated the charity and rose to become its director in Gaza only to use his position to funnel £5.3 million a year to the militant group.

Around 60 per cent of the funds meant to ease suffering in the Gaza Strip were instead diverted to paying Hamas salaries and readying the group for war with Israel, according to the Shin Bet, the Israeli equivalent of MI5.

World Vision denied the allegations but the case casts a harsh spotlight on one of the world’s biggest charities.

The group has an annual budget of more than £2 billion and a roster of celebrity backers that includes Bill Clinton, Scarlett Johansson and Justin Bieber.