Plan UK has reported the theft of supporter data including names, bank details, addresses and phone numbers, after five computer servers were taken during a break-in.

The charity, which works with children in poor countries, will contact thousands of supporters to inform them of the situation. It said that “security measures” meant that obtaining supporter information from the files would be extremely difficult.

Plan UK has more than 90,000 supporters sponsoring 96,000 children. It received around £27m last year in income from sponsorship, donations and legacies, and recently posted a 27 per cent increase in income.

“On the evening of Sunday 22 November, there was a break-in at the Plan UK office in London, during which entry was forced into a locked server room and five computer servers stolen,” the charity’s chief executive Tanya Barron said in a statement.

“These servers contained some information relating to supporters, including name, address, contact details, bank account numbers and sort codes. This information on its own cannot be used to access supporters’ bank accounts. No credit or debit card details were obtained.

“We are contacting supporters to inform them of the situation and provide advice.

“Security measures on the data held means that obtaining the supporter information in these files would be very difficult.”

A police investigation is under way. The charity has also notified the Information Commissioner’s Office and the Charity Commission.