Leader of the opposition Ed Miliband expresses his shock at the possibility that Conservative party donors has been able to buy influence:

"These are very disturbing revelations. The Conservative party has been seeking cash in exchange for access to the prime minister and chancellor and indeed influence over policy making.

"It can't just be an internal Conservative investigation sweeping it under the carpet and keeping it out of the public view. There can't just be an internal Conservative party inquiry into itself.

"These allegations concern the way that policy is made – including in a Budget last week where the tax rate has been cut at the top of the income scale.

"What we've heard about today really falls way below the standards the British people are right to expect."