* Li's firms say he has full confidence in Postal Savings Bank
* Sees PSBC as long-term investment
* Li Ka Shing Foundation backs healthcare and education projects (Adds background on China media's criticism of Li)
HONG KONG, Sept 29 (Reuters) - Hong Kong's Li Ka Shing Foundation has disclosed a 2.8 percent interest in Postal Savings Bank of China Co Ltd, a state-backed lender that raised $7.4 billion through an initial public offering in Hong Kong this month.
The ownership arises from performance-linked notes issued by a financial institution, the foundation said in a statement, without elaborating. The indirect stake is worth HK$10.78 billion ($1.39 billion), according to a Reuters calculation based on Thursday's closing price of the bank's stock.
The foundation of Hong Kong billionaire Li Ka-shing has rarely disclosed the details of its investment portfolio in the past. Li's interest in Postal Savings Bank comes at a time when he has come under fire from Chinese state media for divesting billions of dollars of investments from mainland China.
In one of several critical articles, the People's Daily, the Chinese Communist Party's official mouthpiece, published an editorial late last year on its social media account calling Li's actions "immoral" and "unpatriotic".
Commentators and political observers said the article suggested the politically connected Li, who had enjoyed close ties with the likes of former president Jiang Zemin, had lost some political support from Beijing. Li himself has since said that he resolutely supports China and its president Xi Jinping.
Hong Kong tycoon Li has "absolute" confidence in the bank and treats the ownership as a long-term investment, his group companies CK Hutchison Holdings Ltd and Cheung Kong Property Holdings Ltd said separately in a joint statement.
The Li Ka Shing Foundation was established in 1980 and mostly supports healthcare and education projects across 27 countries and regions, according to its website. It has deployed over HK$20 billion so far to support these initiatives, 87 percent of which benefit projects in the greater China region, it said.
Postal Savings Bank shares made a flat debut on Wednesday and were little changed on Thursday. The lender is among the last of major Chinese state-owned banks to go public. ($1 = 7.7540 Hong Kong dollars) (Reporting by Denny Thomas and Donny Kwok; Additional reporting by James Pomfret; Editing by Chris Cushing and Muralikumar Anantharaman)