REUTERS - Singapore shares headed lower for the fifth straight day, in line with regional markets, as investors cautiously watch the fight over the United States budget, which could hurt the recovery of the world's top economy.

The US Congress is currently struggling to pass a spending bill to keep the government funded beyond Oct 1, but that is just a taster for the fight over raising the debt limit.

The benchmark Straits Times Index fell as much as 0.8 per cent to a one-week low of 3,183.26 points in trading volume just about a quarter of the average turnover over the past month.

MSCI's broadest index of Asia-Pacific shares outside Japan fell 0.2 per cent.

Hutchison Port Holdings Trust, which operates container terminals, rose to as high as US$0.79 (S$0.985), matching a more than three-month high hit on Wednesday. HPH Trust shares had already risen nearly 7 per cent so far this month, on course for their biggest monthly gain since last October, supported by warming sentiment on the shipping market.

DBS Vickers Securities initiated coverage on Soilbuild Business Space REIT with a "buy" call and a target price of $0.87.

"Compared to existing industrial S-REITs, its portfolio is the youngest," said DBS in a research note.

"SB REIT will derive 42-43 per cent of its net property income from master leases, with tenures ranging from 5-15 years, and this will offer strong income visibility to the REIT." SB REIT, which debuted on the SGX in August with an initial offering price of $0.78, rose as much as 1.4 per cent to $0.745.