CAIRO Egypt's non-oil private sector shrank for the 34th straight month in September as a slowdown at ports and low consumer demand caused company backlogs to jump at the fastest rate in years, a survey showed on Tuesday.

The S&P Global Purchasing Managers' Index (PMI) fell to 48.7 from 49.2 in August, dropping further below the 50.0 threshold that separates growth from contraction.

"Egyptian non-oil companies faced unprecedented pressure on their operating capacity in September despite sales continuing to fall," S&P Global economist David Owen said. The PMI Backlogs of Work Index signalled a record pile-up of incomplete orders, he added.

The backlog index jumped to 53.1, its highest reading since the PMI began in April, 2012, from 51.0 in August.

"Firms frequently reported that the high-inflationary environment - annual urban inflation reached a record high of 37.4% in August - and a lack of raw material supply meant they were often unable to fulfil client orders," Owen added.

"Firms faced delays in the arrival of inputs for the first time in three months, which was largely attributed to longer customs procedures," S&P Global said.

The output subindex fell to 45.7 from 48.0 in August, while new orders slipped to 47.6 from 48.3.

The subindex for future output expectations edged down to 53.0 from 53.7 in August.

(Reporting by Patrick Werr; Editing by Hugh Lawson)