Sir Mark Walport, director of the Wellcome Trust, has been moved to defend the charity’s recent investment in the online lender Wonga after being tackled about it by Labour MP Stella Creasy.

Sir Mark has claimed the company has a completely different business model to payday lenders, who have attracted criticism for giving sky-high interest-rate loans.

Sir Mark makes the defence in a letter to Creasy (pictured) who is leading a campaign against payday lending, after she asked Sir Mark whether the Wellcome Trust considered the wider social implications of investing in Wonga.

In the letter to Creasy, seen by civilsociety.co.uk, Sir Mark said he shared her concerns over the payday loan industry, but felt it was "misleading" to compare Wonga with payday lenders who had a completely different business model.

“We have found the company to be extremely engaging and always willing to listen to feedback,” Sir Mark said.

Creasy is leading a campaign to introduce a cap on the credit charged by high-rate lenders. This week, she is meeting Treasury ministers to discuss ways of tackling the problems associated with high-cost lending.

Creasy said: “I will be pushing for legislation introducing a range of caps on the cost of credit when I meet the Treasury minister Mark Hoban this week, and looking at what else can be done to affect the way this industry currently causes problems for people across our country.

“There is strong cross-party support for action so I will continue to press for Parliament to have the opportunity to make this happen.  Britain's consumers deserve the same protection from these exploitative practices as other consumers across the world.”