South African private sector activity expanded slightly in August as higher new orders supported output and purchasing, a business survey showed on Thursday.

The S&P Global South Africa Purchasing Managers' Index (PMI) rose to 50.5 in August from 50.3 in July.

The 50 mark separates growth from contraction.

New orders increased marginally, with surveyed businesses reporting larger orders, successful tenders and rising sales as customer finances improved.

Output expanded for a second month and at the strongest pace since April. Purchasing activity also rose at the quickest rate since March, helping lift input stocks at the fastest pace in four months.

Export sales were only just in positive territory and hit a three-month low, the survey showed.

"Survey comments suggest that business expectations also rely on a recovery of both domestic and external economic conditions, implying the path to stronger growth remains unclear," said S&P Global Market Intelligence Senior Economist David Owen.