LONDON, Sept 28 (Reuters) -

A $1 billion metals deal by blank-cheque fund ACG Acquisition Company has been terminated following delays when the different sides, which included a leading global miner and top automakers as anchor investors, tried to revise it, ACG said on Thursday.

ACG, a London-listed special purpose acquisition company (SPAC), planned to buy a nickel mine and a copper mine from Appian Capital, betting on rising demand for metals needed for the global green energy transition.

In June, global miner Glencore, Chrysler parent Stellantis and Volkswagen's battery unit PowerCo agreed to back the deal through an equity investment. It was expected to close in August.

"ACG announces today that, despite its best efforts, revisions to the Acquisition Agreement have not been agreed and the Acquisition Agreement has been terminated," ACG said in a statement.

ACG and Glencore declined to comment.

Weak economic data from the world's largest metals consumer China, which it has reported since August, affected the investors' appetite for the deal, a source, directly familiar with the situation, told Reuters.

Nickel prices slumped by 37% so far this year, while copper is down 2%.

"The deal fell apart over price. Appian wanted more for the mines than the buyers considered realistic, especially since the nickel price has declined," another source, familiar with the situation, said.

Appian did not reply to a Reuters' request for comment.

SPACs are shell companies that raise money via an initial public offering (IPO) and later merge with a private company, taking it public. ACG would have been the first mining SPAC listing in London.

There has been also a lack of interest from minority investors at the stage of the $300-million equity offering which ACG planned as part of the deal, despite the presence of Stellantis and Glencore as anchor investors, a banking source said.

A year ago, Appian began legal proceedings in a $1.2-billion claim against South Africa's Sibanye-Stillwater after Sibanye pulled out of a deal to acquire the same two mines. (Reporting by Polina Devitt and Clara Denina; editing by Timothy Gardner)