By Christina Amann and Rachel More

HANOVER, Germany, Sept 11 (Reuters) - Germany's IG Metall is demanding Volkswagen commits to honouring a landmark labour ‌deal struck in 2024, a leading union representative said, citing ‌fears that a recent turnaround agreement could undermine it with mass job losses.

IG Metall members on ​Friday decided to invoke a legal clause, which was part of the agreement reached in December 2024, to that effect, Thorsten Groeger told reporters in Hanover.

The move marks an escalation in the fight for Volkswagen's future, which has pitted ‌management against the group's ⁠labour and state government stakeholders over a plan to roughly double layoffs to some 100,000 and drastically cut production.

Volkswagen did ⁠not immediately comment on the move.

"This uncertainty cannot continue for the workforce at our locations," said Daniela Cavallo, Volkswagen works council chief.

The 2024 deal, which was agreed ​after ​mass walkouts, resulted in 35,000 layoffs and ​wage concessions, but fended off ‌immediate plant closures while securing certain job and investment guarantees from management.

IG Metall is prevented from holding strikes until the end of the year under existing labour agreements.

Tensions between the two sides flared again in recent months over CEO Oliver Blume's overhaul plans, including four threatened plant closures early next ‌decade, as Europe's top carmaker battles Chinese ​competition, mounting tariff payments and high manufacturing costs.

Cavallo ​said management's criticism of German ​manufacturing costs was "finger-pointing". She called more broadly for policies to ‌protect industry against heavily subsidised competitors ​from China, such ​as an expansion of EU tariffs to cover Chinese-made plug-in hybrids and local content rules for car components.

"We the automotive industry are in ​fierce competition, with players ‌who are entering the market under completely different competitive conditions - conditions ​that we simply cannot keep up with," the labour chief said.

(Editing ​by Christoph Steitz and Miranda Murray)