* HK fund wants Toshiba to renegotiate or list the chip unit
* HK fund Argyle has just $1.3 bln under management
* Unclear how much support Argyle has from other investors
* Toshiba has no plans to cancel sale unless drastic changes occur (Recasts and writes through)
TOKYO, April 6 (Reuters) - A Hong Kong-based activist investment fund opposed to Toshiba Corp's $18 billion sale of its chip unit to a Bain Capital-led group said the business was worth as much as double its agreed price and the deal should be renegotiated.
Toshiba now has the option to cancel the sale without penalty as the deal failed to close by an agreed deadline of March 31. The two sides are still waiting on regulatory approval from China.
Argyle Street Management, with $1.3 billion under management, has been urging Toshiba to reconsider and opt to list the prized unit instead. While the fund says it has other activist investors on its side, it is not clear how much support it has. It has also not disclosed the size of its stake in Toshiba.
The fund said in a statement on Friday that the unit, which is due to be sold for some 2 trillion yen ($18.6 billion) should be renegotiated at a valuation of 3.3 trillion yen to 4.4 trillion yen.
A Toshiba spokeswoman said the company was still waiting for regulatory approval on the deal, and that its stance was to wait. She declined to comment on the Argyle statement.
Toshiba Chief Executive Nobuaki Kurumatani told reporters earlier this week that the company had no plans to cancel the sale unless there were "major material changes" in circumstances.
The Bain consortium last year won a long and highly contentious battle for the unit, which Toshiba put up for sale after billions of dollars in cost overruns at its Westinghouse nuclear unit plunged the Japanese conglomerate into crisis.
While the sale of the chip unit was once thought necessary to rescue Toshiba from insolvency and a delisting, the conglomerate no longer needs the funds as much, having raised $5.4 billion from a share issue to foreign investors late last year.
($1 107.31 yen) (Reporting by Makiko Yamazaki and Taro Fuse; Writing by Ritsuko Ando; Editing by Edwina Gibbs)