Operating conditions across Singapore's private sector expanded at a weaker pace in September, with the headline S&P Global Singapore Purchasing Managers' Index (PMI) coming in at 58.1, according to data released on Monday.

The latest reading, which tracks overall private-sector economic activity, came slightly lower than the record 59.4 print in August.

A reading above 50 indicates expansion in private-sector performance, while a figure below signals contraction.

The monthly growth momentum was primarily driven by a strong demand environment, more customers, and increased business development, boosting new work inflows for Singaporean private sector firms.

Meanwhile, supply conditions deteriorated, and costs rose, prompting firms to raise output charges at one of the fastest rates on record, S&P said.