* Elliott says plan not enough to fix 'valuation discounts'
* Elliott urges shareholders to vote against plan
* Hyundai Motor, Mobis previously announced share cancellations (Adds Elliott comment, background)
SEOUL, May 11 (Reuters) - U.S. activist fund Elliott Management said late on Thursday that it will vote against Hyundai Motor Group's restructuring plan and urged other shareholders to vote against the plan for South Korea's second-largest conglomerate.
Hyundai Motor Group in March unveiled reforms aimed at simplifying its complex ownership structure, which will be put to a shareholder vote on May 29.
Elliott said in a statement it believes the restructuring plan is "based on flawed assumptions," adding that the conglomerate's recent "token measures" on share buybacks and cancellation of existing shares, while positive, were not enough.
"More significant measures are needed to address the long-unresolved issues at the Group that have led to significant valuation discounts and underperformance at Hyundai Mobis, Hyundai Motor and Kia," Elliott said.
A spokeswoman for Hyundai Motor did not have an immediate comment.
Under the plan, auto parts maker Hyundai Mobis will spin off its domestic module and after-service parts businesses and merge them with Hyundai Glovis, a logistics firm.
Elliott, which disclosed in April that it holds more than $1 billion worth of shares in three key affiliates of Hyundai Motor Group, previously called on the company to adopt a holding company strategy and appoint more independent board members.
Hyundai Motor said in late April it will cancel $890 million worth of treasury shares, its first stock cancellation in 14 years, while Hyundai Mobis said earlier this month it would cancel about 600 billion won ($557.21 million) in treasury shares from next year and pay dividends in more installments. (Reporting by Joyce Lee and Hyunjoo Jin; editing by Phil Berlowitz and Cynthia Osterman)