(Reuters) - Singapore Airlines Ltd said on Thursday it had raised $600 million in a U.S. dollar bond deal to help fund aircraft purchases and repay existing borrowings as it grapples with lower travel demand amid rising Omicron infections.

The seven-year notes, its second U.S. dollar bond offering, have a coupon of 3.375%. A year ago, it raised $500 million in a five-year issue with a 3% coupon.

The airline was aiming to raise between $500 million and $750 million, two sources with direct knowledge of the matter told Reuters on Tuesday.

The Singapore government last month froze the sale of tickets for arriving flights under its quarantine-free travel programme for four weeks, citing the risk from the fast-spreading Omicron COVID-19 variant.

Before this offering, the airline had raised S$21.6 billion ($16 billion) of liquidity during the pandemic and had untapped debt facilities of S$2.1 billion as of Sept. 30, according to its latest financial results presentation.

Despite the fall in demand, it has been spending billions of dollars renewing its fleet to help lower fuel burn and carbon emissions.

($1 = 1.3459 Singapore dollars)

(Reporting by Jamie Freed in Sydney; Editing by Himani Sarkar)