UPDATE 1-Thyssenkrupp, workers strike deal to pave way for steel merger

* Job, site security until Sept. 30, 2026

* Deal removes major hurdle to planned Tata Steel deal

* Thyssenkrupp to keep stake in JV for at least six years (Recasts, adds CEO comment, details on agreement)

DUESSELDORF, Dec 21 (Reuters) - Workers on Thursday struck a deal with Thyssenkrupp to secure steel plants and jobs, a key step towards a planned merger of the group's European steel business with that of India's Tata Steel .

The agreement, which still needs to be approved by IG Metall's members, foresees no forced layoffs or major site closures until Sept. 30, 2026, labour representatives and the group said.

This comes close to meeting the demands of IG Metall, Germany's most powerful union, which had asked for 10 years, concerned that the company was shirking responsibility for the volatile steel business by merging it with a peer.

Thyssenkrupp and Tata Steel in September reached a preliminary agreement to merge their European steel units to create the continent's second-largest steelmaker after ArcelorMittal.

"The outcome achieved today represents a key prerequisite for meeting our strategic objectives and at the same time satisfying the interests of our employees," Thyssenkrupp Chief Executive Heinrich Hiesinger said.

Under the deal, Thyssenkrupp will keep a stake in the joint venture for at least six years, adding a change in the entity's shareholder structure during that time, possibly as the result of a stock market listing, could not be ruled out. (Reporting by Matthias Inverardi and Tom Kaeckenhoff; Writing by Christoph Steitz; Editing by Jane Merriman)