HONG KONG (Reuters) - HNA Group, the Chinese airline-to-banking conglomerate, has tapped investment bank Goldman Sachs (>> Goldman Sachs Group) to list Pactera, the Beijing-based IT outsourcing firm it bought from private equity firm Blackstone, sources familiar with the matter said.

The mandate for the U.S. initial public offering of Pactera, bought for $675 million in cash last year, is not yet official, the sources said, but the listing could come early next year.

News of the appointment of Goldman Sachs, a Wall Street stalwart, is a boost for HNA, even if the mandate is not official. The sprawling conglomerate has seen its banking relationships come under scrutiny in recent weeks, as Beijing reins in what it sees as excessively splashy deals by China's top dealmakers.

One of the sources said Pactera could see a $200 million pre-IPO funding round close in the third quarter, adding Goldman bankers had spoken to several Chinese institutional investors. Some global private equity firms could also be part of that, particularly those that lost out to Blackstone when it bought the business in 2014, the source said.

The funds raised from the pre-IPO round would be used for a small acquisition deal that Pactera is trying to close in the United States, as well as debt repayment, the source added.

Goldman advised HNA on the acquisition of Pactera.

Pactera did not respond to requests for comment. HNA and Goldman declined to comment.

On Monday, HNA brushed off concerns that some Wall Street banks were shying away from its business, and said it maintained a strong working relationship with key banks including JPMorgan (>> JP Morgan Chase & Company), UBS (>> UBS Group AG) and Morgan Stanley (>> Morgan Stanley).

Several of the banks have long-standing relationships dating back to HNA's days as a regional airline.

But Bank of America Merrill Lynch (BAML) pulled back, citing HNA's opaque ownership structure, according to the New York Times. The Wall Street Journal on Monday quoted an HNA letter to BAML questioning that decision.

HNA Chief Executive Adam Tan said on Monday that BAML had not dealt closely with the group, in any event. HNA also announced a shareholding shake-up in a bid to quash concerns over its ownership.

BAML declined to comment.

Last month, China's banking regulator ordered a group of lenders to assess their exposure to a number of the more aggressive dealmakers, including HNA, property-to-film conglomerate Dalian Wanda and Anbang Insurance Group.

Tan described the checks as "routine".

HNA's relationships have since been closely scrutinized, however, given key funding needs and some of its more sensitive connections, including to Anthony Scaramucci, the newly appointed communications director for the Trump administration.

Scaramucci agreed in January to sell his hedge fund SkyBridge Capital LLC to HNA to clear the way for a job working with U.S. President Donald Trump. That role finally materialized last week.

He said last week that the sale was awaiting U.S. regulatory approval.

(Reporting by Kane Wu and Julie Zhu in HONG KONG; Editing by Clara Ferreira Marques and Muralikumar Anantharaman)

By Kane Wu and Julie Zhu