Top executives from the UK’s six largest energy companies are expected to face serious criticism when they come before a group of MPs.
The bosses have been called in front of the Energy and Climate Change Committee, following recent price rises.
So far, four companies have announced increases that average 9.1%.
The energy firms are expected to insist that the rises were largely due to increasing wholesale prices.
But Andrew Wright, the acting chief executive of regulator Ofgem, is expected to tell the MPs that wholesale prices have risen by less than the rate of inflation.
Ofgem data suggests that wholesale electricity and gas together have risen by just 1.7% over the last year.
It estimates the net effect of wholesale gas prices on a household bill should be just £10 extra on a bill of £600.