ROME, Nov 16 (Reuters) - An Italian administrative court on Wednesday rejected an appeal by energy companies against a government-imposed windfall tax, saying the court had no jurisdiction over the matter. The appeal against the prime minister's office and the tax collection agency was filed by ERG with the backing of several energy sector associations. The windfall tax, introduced by former Premier Mario Draghi's government, was designed to fund measures to shield firms and families from surging energy prices in the wake of the war in Ukraine.

Draghi's successor, Giorgia Meloni, has pledged to introduce next year a new windfall tax with a revised structure amid complaints, legal challenges and refusals to pay from several energy firms.

State-controlled energy group Eni recently said it had appealed against the Italian windfall tax, adding that a framework proposed by the European Union for the levy would be more transparent and fairer.

Eni has paid the first instalment of the tax and should make a second payment by the end of November for a total of 1.4 billion euros ($1.45 billion).

Data on revenue raised by the levy until end-August point to total proceeds of 50% less than the 10 billion euros Draghi's government initially expected. ($1 = 0.9626 euros) (Reporting by Antonella Cinelli; Writing by Alvise Armellini and Francesca Landini; Editing by Gianluca Semeraro and Josie Kao)