BRUSSELS: European Union governments should prepare for a "prolonged disruption" to energy markets as a result of the Iran war, the bloc's energy chief has told countries' ministers ahead of an emergency meeting on Tuesday.

In a letter to energy ministers, dated March 30 and seen by Reuters, EU Energy Commissioner Dan Jorgensen said governments were "encouraged to make timely preparations in anticipation of a potentially prolonged disruption".

Europe's heavy reliance on imported fuel means the continent is very exposed to the Middle East conflict's impact on global energy prices. European gas prices have jumped more than ​70% since the U.S.-Israeli war on Iran began on February 28.

The bloc's supplies of crude oil and natural gas have not been hit directly by the closure of key shipping route the Strait of Hormuz, since Europe imports most of those energy sources from suppliers outside of the Middle East.

However, Jorgensen said Brussels was particularly concerned in the short term about Europe's supply of refined petroleum products such as jet fuel and diesel.

Governments should avoid taking any measures that would increase fuel consumption, limit trade of petroleum products, or disincentivise output at European refineries that handle these products, the letter said.

"Member States are encouraged to defer any non-emergency refinery maintenance," the letter added.