PARIS (Reuters) - France's manufacturing sector remained stuck in decline in October as factory output fell at its fastest rate in nine months, dragged down by low new orders, particularly from international clients, a survey showed on Monday.

The HCOB France Manufacturing Purchasing Managers' Index (PMI), compiled by S&P Global, came in at 44.5, slightly down from 44.6 in September. Readings below 50.0 indicate a contraction in activity.

"The French manufacturing sector remains mired in a deep crisis," said Dr Tariq Kamal Chaudhry, Economist at Hamburg Commercial Bank AG. "The outlook remains bleak, with no sign of an upward trend on the horizon."

A sub-index measuring factory output fell to 43.1, down from 44.0 last month and the worst reading since January when it stood at 41.0.

The downturn was exacerbated by a steep fall in export orders, which decreased at one of the fastest rates in the survey's history amid geopolitical tensions and a slowing global economy.

Domestic demand also weakened, with cautious consumer spending and a struggling construction sector cited as factors by polled company executives.