U.S. diesel prices are up by almost 9 cents per gallon this week, to $3.943 from $3.856. This is the biggest weekly increase since mid-November, according to numbers from the Energy Information Administration's gas and diesel fuel update.

The price of diesel saw increases in every region of the U.S., with Midwest prices rising the most at an average of more than 10 cents.

Gasoline prices are up by 4 cents to a $3.523 national average from $3.482. Prices rose in all regions except the Midwest, where prices dropped by less than half a cent.

Crude oil futures ended $2.24 higher at $100.91 a barrel, the highest in almost five weeks. This is most likely a result of the market's optimism in regard to Greece's vote on austerity measures.

MarketWatch reported: "With disaster seemingly diverted (well, postponed) by this vote, the flame of risk appetite has been fanned, and the euro and equities are hot to trot," said analyst Matt Smith, with Summit Energy, in a note to clients.

Also affecting prices are concerns about supplies following Israel's accusation that Iran is involved in an embassy attack in India and an attempted attack in Georgia.