Logo of HSBC bank Adam Jeffery | CNBC

HSBC, one of the world's biggest banks, has "glaring problems" and may need to plug a $111 billion capital gap, a controversial new report claims. Two analysts for Forensic Asia, a recently launched boutique Hong Kong research firm, have heavily criticized the bank for "overstated earnings, inadequately capitalized balance sheets, legal and regulatory problems" in a research note this week.

HSBC is generally viewed as one of the U.K.'s best-placed banks, and came through the financial crisis without having to raise extra capital, thanks in large part to the global scale of its operations. It had a tier 1 capital ratio – a key measure of financial health – of 13.3 percent at the end of the third quarter of 2013 – far above the 4 percent required by international regulators. (Read more: HSBC profits up, but forex probe casts shadow) Yet the Forensic Asia analysts, Thomas Monaco and Andrew Haskins, argue that it has overstated its balance sheet, with "questionable assets" worth between $63.6 billion and $92.3 billion – or between 4.7 and 6.8 years worth of post-tax results. This means the bank must raise $58 billion to $111 billion by 2019 to meet new, more stringent capital requirements, they argued. (Read more: HSBC UK spin-off will have to join the queue)