EDF Energy reported a solid rise in its UK profits after hiking household energy bills at the beginning of 2014.

The French energy giant, one of the so-called "Big Six" suppliers, said its earnings before tax and other deductions jumped 9.3% in the first six months of the year when compared with the same period in 2013, reaching €1.174bn (£931m, $1.57bn).

It said better output from its nuclear energy operations in the country helped drive up profit, as well as a 3.2% rise in its household customers to 5.6 million accounts.

In January, EDF hike its gas and electricity bills by 3.9% on average. It followed an 11% increase the year before.

Household energy bills are the subject of heated political debate in the UK, where consumer incomes have been squeezed by weak pay growth that is failing to keep up with cost of living increases.

Big energy firms have been accused of profiteering and taking advantage of their dominance in the market. The Big Six will are the subject of a competition inquiry by energy regulator Ofgem.

But the industry defends itself and says it needs to raise bills when its wholesale costs increase and because of the heavy investment needed to maintain and upgrade the UK's creaking energy infrastructure.

Labour party leader Ed Miliband has pledged to force energy firms to freeze bills for nearly two years if he is elected at the 2015 general election.

The governing Conservatives have accused Miliband of conning the public with his pledge; they argue energy firms will simply hike their bills by much more before or after a freeze.

Instead they have promised to shift green levies on energy firms, which pay for schemes such as house insulation, on to general taxation. Because these levies are passed down to consumers via their bills, the Conservatives say this should lower the cost of energy for households.