HONG KONG/TOKYO (Reuters) - The Bain Capital-led consortium that bought Toshiba’s chip unit for $18 billion last week has filed for antitrust approval in China, a source familiar with the matter said, but it may have to wait nine months or more for a green light.

Logo of the Bain Capital is screened at a news conference in Tokyo, Japan September 28, 2017. REUTERS/Kim Kyung-Hoon

Toshiba is keen to complete the sale by the end of its fiscal year in March: it hopes to use the proceeds to plug a gaping balance sheet hole left by its now bankrupt U.S. nuclear subsidiary, and save itself from a potential delisting.

With the clock ticking, the request for antitrust approval was filed the day after the deal was signed, the source said.

But several sources familiar with the matter said the strategic nature of the semiconductor industry for China and political issues - including tense relations with South Korea, and the presence of SK Hynix 000660.KS in the consortium - could delay China's already lengthy regulatory process.

The sources could not be named as they were not authorized to speak to the media.

China’s relationship with South Korea has soured over South Korea’s decision to install a U.S. anti-missile defense system which China deems as a risk to its own national security.

The consortium had anticipated issues around SK Hynix, though largely around antitrust clearance. As part of the deal, SK Hynix can access only limited information and is not allowed to own more than 15 percent of voting rights for 10 years.

Yet China, where both Toshiba and SK Hynix have factories, often takes a broad view of antitrust decisions and industry sources and analysts said Beijing was expected to take a close look at a deal which involves the world’s second-biggest producer of NAND chips.

It could push for a concession, divestment or investment. An outright rejection, threatening the deal, is seen as unlikely.

“Geopolitics probably will be a factor in the process. If you can convince them it’s good for China, it could be easier,” said one of the sources.

The sources confirmed China could normally take 6-9 months to approve a deal, but said the Bain-led consortium was still confident it could secure a timely antitrust approval.

Besides China, the deal would also need antitrust clearance from authorities elsewhere, including Japan, the European Union and the United States.

A delay would not automatically mean a delisting for Toshiba - Japan-based sources said it would have to turn to stopgap measures to plug the gap, including a capital injection.

“The banks would support Toshiba as long as they are confident that Toshiba would eventually get the money from the chip unit sale,” a second source said.

A spokeswoman for Bain declined to comment. Bain is due to hold a press conference in Tokyo on Thursday.

Contacted by Reuters, Toshiba said it intends to close the deal by the end of March, after receiving regulatory approvals.

China’s Ministry of Commerce (MOFCOM) - usually considered China’s main antitrust regulator, even if other entities step in - did not reply to a request for comment during a holiday week.

Toshiba sold its unit last Thursday to a group that includes Bain and SK Hynix, as well as Apple Inc AAPL.O, Dell, Seagate Technology Plc STX.O and Kingston Technology.