PARIS, Dec 14 (Reuters) - The final flight of Italy's Vega rocket has been delayed after crucial parts went missing, while the latest test of Europe's new Ariane 6 has been aborted, the European Space Agency said, the latest glitches to affect Europe's troubled launch sector.

The aborted test of the upper stage of Ariane 6 should not affect plans for an inaugural launch in mid-2024, ESA said.

Europe is racing to restore independent access to space after Ariane 6 suffered repeated delays and the Vega C was grounded after a launch failure, leaving a handful of launches of the original Vega version of the rocket.

Vega's final lift-off had been set for spring 2024, but that has been delayed to September after two out of four of its large propellant tanks disappeared from a factory in Italy, ESA officials told a news conference.

The loss was first reported by specialist publication European Spaceflight, which said the tanks had been found "crushed" and unusable in a landfill, alongside scraps of metal.

Because there are no spares, other than ones used in testing, which could be risky to re-use, the plan is to adapt slightly larger tanks designed for the more recent Vega C model, said Toni Toker-Nielsen, ESA's director of transportation.

He said the lost Vega tanks had not been stolen, but had no explanation as to how they ended up in a garbage dump.

According to the French space agency, Vega runs on propellant stored in four spherical 142-litre tanks.

Vega C failed on its second mission just under a year ago, destroying two imaging satellites. It will return to flight between mid-November and mid-December 2024, Toker-Nielsen said.

For the larger Ariane 6, the hot-firing test of the upper stage at Lampoldshauen in Germany on Dec. 7 was designed to study operating limits in degraded conditions and other factors.

"Unfortunately we had an abort two minutes into the firing test," Toker-Nielsen told reporters.

Manufacturer ArianeGroup is analysing the reasons, he said, adding there were no signs that the aborted test would delay the inaugural flight, scheduled for mid-June to end-July 2024.

ArianeGroup, co-owned by Airbus and Safran , was not immediately available for comment.

ESA said last month a long-firing engine test had been carried out successfully at a launchpad in French Guiana, allowing it to pick a launch window in 2024.

A further loading test will go ahead as planned on Friday. (Reporting by Tim Hepher. Editing by Gerry Doyle)