SYDNEY, May 31 (Reuters) - Hong Kong's government is aiming to raise $4 billion to $6 billion in a multi-currency green bond deal, according to two sources with direct knowledge of the matter.

The sources could not be named as the information is confidential.

The Hong Kong government referred a request for comment to the city's Monetary Authority, which said the "relevant details will be announced in due course".

The deal consists of 3-, 5- and 10-year dollar green bonds, according to a term sheet seen by Reuters.

Investors had already lodged orders worth $9 billion for the U.S. dollar tranche, according to a bookrunner's message seen by Reuters.

A separate term sheet showed the government is also carrying out an offshore Chinese yuan green bond with 2-, 5- and 10-year tenors.

Hong Kong also plans to issue a Euro green bond, according to the sources, but details will be released later on Wednesday.

The deal is the second green bond carried out by the city this year after it raised $5.75 billion worth of bonds in dollars, euros and green bonds in January.

Initial price guidance has been set at Treasuries plus 65 basis points (bps) for the 3-year dollar bond, Treasuries plus 70 bps for the 5-year and Treasuries plus 80 bps for the longer-dated bond, the term sheet showed.

For the offshore yuan tranche, price guidance is set at 3.15% for the 2-year, 3.4% for the 5-year and 3.7% for the 10-year bond.

Hong Kong's government plans to use the funds raised to finance projects that provide "environmental benefits and support the sustainable development" of the city, according to the term sheet. (Reporting by Scott Murdoch; Editing by Tom Hogue, Shri Navaratnam, Varun H K and Sonia Cheema)