* HNA says staff bought bonds backed by the group
* Amount of bonds purchased not clear
* HNA says group in a very healthy financial position
* S&P lowers HNA credit profile on deteriorating liquidity (Adds S&P downgrading of HNA Group, units)
HONG KONG, Feb 14 (Reuters) - China's debt-laden HNA Group said some of its board directors and senior managers have bought offshore dollar bonds guaranteed by the conglomerate - the latest in a series of measures it is taking to shore up its finances.
The aviation-to-financial conglomerate did not give the names of those buyers in the statement, nor the value of the dollar bonds purchased. It declined to provide any additional information when contacted by Reuters.
The development comes as S&P Global Ratings downgraded the credit profile of HNA Group and two of its units, citing the conglomerate's "deteriorating liquidity profile" amid a slew of debt maturities this year.
After announcing $50 billion of deals over two years, HNA was, like other Chinese conglomerates, hit by increased scrutiny of its finances as Beijing grew wary of what it saw as some irrational acquisitions.
Hainan-based HNA has since said it would sell some of its assets, and this week it announced a $2 billion deal for two Hong Kong land parcels. Sources have said it is in talks with creditors about its outstanding loans.
In its Wednesday statement, the group said it was in a "very healthy financial position" with total assets of 1.5 trillion yuan ($236 billion) at end-2017, and that the staff purchased the bonds due to "full confidence" in its business prospects.
In the last couple of years, HNA and its group units have issued a slew of bonds, both in China and overseas, to finance some of its acquisitions as well as to refinance some of its maturing debt obligations.
Hainan Airlines Holdings, the group's flagship firm, has bonds issued worth $4.8 billion, denominated in both Chinese yuan and U.S. dollar, according to Thomson Reuters data. About $1.5 billion worth of bonds will mature in 2018.
HNA Group itself has about $16 billion worth of bonds outstanding, of which $2.4 billion will come up for repayment this year and $4.8 billion in 2019, the data showed. A $52-million tranche, issued offshore, will come up for repayment on July 18, 2018.
In November, the group sold a short-dated bond at a coupon of 9 percent, higher than the 8 percent yield indicated on its December 2018 bond, in a sign that it was under pressure to refinance its debt-laden balance sheet.
The yield on a group unit's three-year, December 2018 bond has nearly tripled from a year-ago period, underscoring investors' concerns and significantly raising its future borrowing costs.
In December, senior executives of HNA agreed to purchase $13 million worth of shares in another group subsidiary Bohai Capital Holdings to bolster "investor confidence" and promote stability at the firm.
Bohai Capital is one of many HNA's listed units that have suspended trading in their shares since November pending announcements.
S&P late on Tuesday cut HNA credit profile by one notch to 'ccc+', a "speculative grade".
"This revision reflects our understanding of HNA Group's deteriorating liquidity profile as it faces significant debt maturities in 2018," the rating agency said in its report on the group as well as some units.
"While it appears to have made some progress, and has valuable assets and highly liquid stakes in public traded companies, in our view HNA Group is dependent upon favourable market conditions to meet its upcoming financial commitments."
The rating agency also announced the lowering of credit rating of HNA's IT outsourcing unit Pactera and airline caterer Gategroup Holding, as a result of the downgrading of the parent's credit profile.
S&P expects Pactera's debt leverage to remain high, saying the company would need to raise new funds to meet its upcoming debt obligations.
HNA Group did not immediately respond to a Reuters request for a comment on S&P's move.
($1 = 6.3530 Chinese yuan) (Reporting by Sumeet Chatterjee; additional reporting by Matthew Miller in Beijing; Editing by Edwina Gibbs & Simon Cameron-Moore)