The first batch of SAF was blended in Europe, Shell said in a statement.

"We have delivered some (SAF) to our customers SIA Engineering Company and the Republic of Singapore Air Force," said Doris Tan, head of aviation Asia Pacific & Middle East.

Shell has also completed an upgrade of its Singapore facility, which will enable it to blend SAF in the city-state itself, while it also aims to test the supply chain it is establishing for SAF in Asia.

Aviation, which accounts for 3% of the world's carbon emissions, is considered one of the toughest sectors to tackle due to a lack of alternative technologies to jet fueled-engines.

"Alongside investing in our capabilities to produce SAF, we are also focused on developing the regional infrastructure needed to get the fuel to our customers at their key locations," said Jan Toschka, global president, Shell Aviation.

The SAF supplied is made from waste products and sustainable feedstocks and will be blended at an approved ratio of up to 50% with conventional jet fuel, Shell said.

In its neat form, SAF can reduce lifecycle emissions by up to 80% compared with conventional fuel, it added.

The Singapore Airshow opened to a limited crowd of trade visitors on Tuesday, with organisers expecting the biennial event to attract more than 13,000 trade attendees, many fewer than nearly 30,000 in 2020 and around 54,000 in 2018.

Singapore's civil aviation authority and state-investor Temasek will support the city-state's flagship carrier Singapore Airlines in buying SAF from top U.S. oil producer Exxon Mobil Corp for use in flights, the parties said last week.

(Reporting by Koustav Samanta; Editing by Mark Potter)

By Koustav Samanta